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V 


. ■* 


scoveries 
All Time 


Kendall Hawn 


100 Greatest 
Science Discoveries 
ol All Time 


Kendall Haven 




A Member of the Greenwood Publishing Group 


Westport, Connecticut • London 


Library of Congress Cataloging-in-Publication Data 

Haven, Kendall F. 

100 greatest science discoveries of all time / Kendall Haven, 
p. cm. 

Includes bibliographical references and index. 

ISBN-13: 978-1-59158-265-6 (alk. paper) 

ISBN-10: 1-59158-265-2 (alk. paper) 

1. Discoveries in science. I. Title. II. Title: One hundred greatest 
science discoveries of all time. 

Q180.55.D57H349 2007 
509— dc22 2006032417 

British Library Cataloguing in Publication Data is available. 

Copyright © 2007 by Kendall Haven 

All rights reserved. No portion of this book may be 
reproduced, by any process or technique, without the 
express written consent of the publisher. 

Library of Congress Catalog Card Number: 2006032417 
ISBN: 978-1-59158-265-6 

First published in 2007 

Libraries Unlimited, 88 Post Road West, Westport, CT 06881 
A Member of the Greenwood Publishing Group, Inc. 
www.lu.com 

Printed in the United States of America 



The paper used in this book complies with the 
Permanent Paper Standard issued by the National 
Information Standards Organization (Z39. 48-1984). 


10 987654321 


Contents 


Acknowledgments ix 

Introduction xi 

How to Use this Book xv 

Levers and Buoyancy 3 

The Sun Is the Center of the Universe 5 

Human Anatomy 7 

The Law of Falling Objects 9 

Planetary Motion 11 

Jupiter’s Moons 13 

Human Circulatory System 15 

Air Pressure 17 

Boyle’s Law 19 

The Existence of Cells 21 

Universal Gravitation 23 

Fossils 25 

Distance to the Sun 27 

Bacteria 29 

Laws of Motion 31 

Order in Nature 33 

Galaxies 36 

The Nature of Electricity 38 

Oceans Control Global Weather 40 

Oxygen 43 

Photosynthesis 45 

Conservation of Matter 47 

The Nature of Heat 49 

Erosion of the Earth 51 

Vaccinations 53 

Infrared and Ultraviolet 55 

Anesthesia 57 

Atoms 59 

Electrochemical Bonding 61 

The Existence of Molecules 63 

Electromagnetism 65 

First Dinosaur Fossil 67 

Ice Ages 69 

Calories (Units of Energy) 71 

Conservation of Energy 73 


V 


vi Contents 


Doppler Effect 75 

Germ Theory 77 

The Theory of Evolution 79 

Atomic Light Signatures 81 

Electromagnetic Radiation/Radio Waves 83 

Heredity 86 

Deep-Sea Life 88 

Periodic Chart of Elements 90 

Cell Division 92 

X-Rays 95 

Blood Types 97 

Electron 99 

Virus 101 

Mitochondria 103 

Radioactivity 105 

Atmospheric Layers 107 

Hormones 109 

E = me 2 Ill 

Relativity 114 

Vitamins 117 

Radioactive Dating 119 

Function of Chromosomes 121 

Antibiotics 124 

Fault Lines 126 

Superconductivity 128 

Atomic Bonding 131 

Isotopes 133 

Earth’s Core and Mantle 136 

Continental Drift 138 

Black Holes 140 

Insulin 142 

Neurotransmitters 144 

Human Evolution 146 

Quantum Theory 148 

Expanding Universe 150 

Uncertainty Principle 153 

Speed of Light 155 

Penicillin 158 

Antimatter 160 

Neutron 163 

Cell Structure 165 

The Function of Genes 167 

Ecosystem 169 

Weak and Strong Force 171 

Metabolism 174 


Contents vii 


Coelacanth 176 

Nuclear Fission 178 

Blood Plasma 181 

Semiconductor Transistor 183 

The Big Bang 185 

Definition of Information 188 

Jumpin’ Genes 190 

Fusion 192 

Origins of Life 194 

DNA 196 

Seafloor Spreading 199 

The Nature of the Atmosphere 201 

Quarks 203 

Quasars and Pulsars 205 

Complete Evolution 208 

Dark Matter 211 

The Nature of Dinosaurs 213 

Planets Exist Around Other Stars 215 

Accelerating Universe 218 

Fluman Genome 220 

References 223 

Appendix 1 : Discoveries by Scientific Field 229 

Appendix 2: Scientists 233 

Appendix 3: The Next 40 237 

Index 239 



Acknowledgments 


I owe a great deal of thanks to those who have helped me research and shape these en- 
tries. The librarians at the Sonoma County Public Library and those at the Sonoma State 
Charles Schultz Library have been invaluable in helping me locate and review the many 
thousands of references I used for this work. I owe a special thanks to Roni Berg, the love of 
my life, for her work in both shaping these individual entries and in creating the 100 fun 
facts you will read in this book. Finally, I owe a great thank you to Barbara Ittner, the Li- 
braries Unlimited editor who steadfastly supported and encouraged me to create this book 
and whose wisdom and insights shaped it and are reflected on every page. 


ix 



Introduction 


Discovery! The very word sends tingles surging up your spine. It quickens your pulse. 
Discoveries are the moments of “Ah, ha! I understand!” and of “Eureka! I found it!” 

Everyone longs to discover something — anything ! A discovery is finding or observing 
something new — something unknown or unnoticed before. It is noticing what was always 
there but had been overlooked by all before. It is stretching out into untouched and un- 
charted regions. Discoveries open new horizons, provide new insights, and create vast for- 
tunes. Discoveries mark the progress of human civilizations. They advance human 
knowledge. 

Courtroom juries try to discover the truth. Anthropologists discover artifacts from past 
human civilizations and cultures. People undergoing psychotherapy try to discover 
themselves. 

When we say that Columbus “discovered” the New World, we don’t mean that he cre- 
ated it, developed it, designed it, or invented it. The New World had always been there. Na- 
tives had lived on it for thousands of years before Columbus’s 1492 arrival. They knew the 
Caribbean Islands long before Columbus arrived and certainly didn’t need a European to 
discover the islands for them. What Columbus did do was make European societies aware 
of this new continent. He was the first European to locate this new land mass and put it on 
the maps. That made it a discovery. 

Discoveries are often unexpected. Vera Rubin discovered cosmic dark matter in 1970. 
She wasn’t searching for dark matter. In fact, she didn’t known that such a thing existed un- 
til her discovery proved that it was there. She even had to invent a name (dark matter) for it 
after she had discovered its existence. 

Sometimes a discovery is built upon previous work by other scientists, but more often 
not. Some discoveries are the result of long years of research by the discovering scientist. 
But just as often, they are not. Discoveries often come suddenly and represent the beginning 
points for new fields of study or new focuses for existing scientific fields. 

Why study discoveries? Because discoveries chart the direction of human develop- 
ment and progress. Today’s discoveries will shape tomorrow’s world. Major discoveries 
define the directions science takes, what scientists believe, and how our view of the world 
changes over time. Einstein’s 1905 discovery of relativity radically altered twentieth- 
century physics. Discoveries chart the path and progress of science just as floating buoy 
markers reveal the course of a twisting channel through a wide and shallow bay. 

Discoveries often represent radically new concepts and ideas. They create virtually all 
of the shaip departures from previous knowledge, life, and thinking. These new scientific 
discoveries are as important to our evolution as are the evolutionary changes to our DNA 
that have allowed us to physically adapt to our changing environments. 


xi 


xii Introduction 


This book briefly describes the 100 greatest science discoveries of all time, the discov- 
eries that have had the greatest impact on the development of human science and thinking. 
Let me be clear about exactly what that means: 

Greatest: “Of highest importance; much higher in some quality or degree of under- 
standing” (Webster’s New College Dictionary). 

Science: Any of the specific branches of scientific knowledge (physical sciences, earth 

sciences, and life sciences) that derive knowledge from systematic observation, study, 

and experimentation. 

Discovery: The first time something is seen, found out about, realized, or known. 

All time: The recorded (written) history of human civilizations. 

This book, then, describes the process of finding out, of realizing key scientific infor- 
mation for the 100 science discoveries of the highest importance over the course of re- 
corded human history. These are the biggest and most important of all of the thousands of 
science discoveries. These are the science discoveries that represent the greatest efforts by 
the best and brightest in the world of science. 

There are many areas of human development and many kinds of important discoveries 
not included here — for example, discoveries in art, culture, exploration, philosophy, soci- 
ety, history, or religion. I also excluded science discoveries that cannot be attributed to the 
work of one individual or to a small group of collaborators. Global warming, as an example, 
is a major research focus of our time. Its discovery may be critical to millions — if not bil- 
lions — of human lives. However, no one individual can be credited with the discovery of 
global warming. At a minimum, 30 researchers spread over 25 years each had a hand in 
making this global discovery. So it is not included in my list of 100. 

You will meet many of the giants of science in this book. Many — but certainly not all. 
There are many who have made major contributions to the history and thought of science 
without making one specific discovery that qualifies as one of the 100 greatest. Many of the 
world’s greatest thinkers and discoverers are not here because their discoveries do not qual- 
ify as science discoveries. 

Discoveries are not normally sought or made in response to existing practical needs, as 
are inventions. Discoveries expand human knowledge and understanding. Often, it takes 
decades (or even centuries) for scientists to understand and appreciate discoveries that turn 
out to be critical. Gregor Mendel’s discovery of the concept of heredity is a good example. 
No one recognized the importance of this discovery for more than 50 years — even though 
we now regard it as the founding point for the science of genetics. Einstein’s theory of rela- 
tivity was instantly recognized as a major discovery. However, a century later, scientists 
still struggle to understand what it means and how to use it as we inch farther into space. 

That would not be the case with a great invention. The process of invention focuses on 
the creation of practical devices and products. Inventors apply knowledge and understand- 
ing to solve existing, pressing problems. Great inventions have an immediate and practical 


use. 


Introduction xiii 


Not so with discoveries. Einstein’s theory of relativity produced no new products, 
practices, or concepts that affect our daily life. Neither did Kepler’s discovery of the ellipti- 
cal orbits of the planets around the sun. The same is true of Alfred Wegener’s discovery that 
the continents drift. Yet each represents a great and irreplaceably important advance in our 
understanding of our world and of the universe. 

I had three main purposes in shaping and writing this book: 

1 . To present key scientific discoveries and show their impact on our thinking and 
understanding. 

2. To present each discovery within the continuum of scientific progress and devel- 
opment. 

3. To show the process of conducting scientific exploration through the context of 
these discoveries. 

It is interesting to note that the scientists who are associated with these 100 greatest 
science discoveries have more traits and characteristics in common than do those associ- 
ated with the 100 greatest science inventions (see my book by that title, Libraries Unlim- 
ited, 2005). The scientists listed in this book — those who have made major science 
discoveries — in general excelled at math as students and received advanced degrees in 
science or engineering. 

As a group they were fascinated by nature and the world around them. They felt a 
strong passion for their fields of science and for their work. They were often already estab- 
lished professionals in their fields when they made their grand discoveries. Their discover- 
ies tend to be the result of dedicated effort and creative initiative. They got excited about 
some aspect of their scientific field and worked hard, long hours with dedication and inspi- 
ration. These are impressive men and women we can hold up as model scientists, both fortu- 
nate in their opportunities and to be emulated in how they took advantage of those 
opportunities and applied both diligence and honesty in their pursuit of their chosen fields. 

It is also amazing to consider how recent many of these discoveries are that we take for 
granted and consider to be common knowledge. Seafloor spreading was only discovered 50 
years ago, the existence of other galaxies only 80 years ago, the existence of neutrons only 
70 years ago. Science only discovered the true nature and behavior of dinosaurs 30 years 
ago and of nuclear fusion only 50 years ago. The concept of an ecosystem is only 70 years 
old, That of metabolism is also only 70 years old. Yet already each of these concepts has 
woven itself into the tapestry of common knowledge for all Americans. 

I had to devise some criteria to compare and rank the many important science discover- 
ies since I had literally thousands of discoveries to choose from. Here are the seven criteria I 
used: 

1. Does this discovery represent truly new thinking, or just a refinement and im- 
provement of some existing concept? 

2. What is the extent to which this discovery has altered and reshaped scientific di- 
rection and research? Has this discovery changed the way science views the 
world in a fundamental way? Has it radically altered or redirected the way scien- 
tists think and act? 


xiv Introduction 


3. What is the importance of this discovery to the development of that specific field 
of science? 

4. Has this discovery had long-term effects on human development? Has its impact 
filtered down to our daily lives? 

5. Is this a discovery within a recognized field of science? Is it a science discovery? 

6. Am I adequately representing the breadth and diversity of the many fields, 
subfields, and specialties of science? 

7. Can this discovery be correctly credited to one individual and to one event or to 
one prolonged research effort? 

There are many worthy discoveries and many worthy scientists that did not make the 
final cut to be represented here. All of them are worthy of study and of acclaim. Find your 
own favorites and research them and their contributions (see Appendix 3 for additional 
suggestions). 

Several entries include two discoveries because they are closely linked and because 
neither alone qualifies as one of the 100 greatest. However, considered collectively, they 
take on an importance far greater than their individual impact would suggest. 

Enjoy these stories. Revel in the wisdom and greatness of these discoveries. Search for 
your own favorites. Then research them and create your own discovery stories to share! 


How to Use This Book 


This book provides a wealth of information on — obviously — science discoveries, but 
also on the process of doing science, and glimpses into the lives of the many fascinating 
people who have advanced our scientific knowledge. 

Use the book as a reference for science units and lessons focused on different aspects 
of, or fields of science. Use it to introduce units on discoveries, or on the process of doing 
science. Use it as a reference for science biography research. Use it as an introduction to the 
process of discovery and the process of conducting scientific study. Use it for fun reading. 

Each entry is divided into four sections. An introductory section defines the discovery 
and lists its name, year of discovery, and discovering scientist. This is followed by a brief 
justification for placing this discovery on the greatest 100 list (“Why Is This One of the 100 
Greatest?”). 

The body of each entry (“How Was It Discovered?”) focuses on how the discovery 
was made. These sections provide a look at the process of science and will help students ap- 
preciate the difficulty of, the importance of, and the process of scientific discovery. Follow- 
ing this discussion, I have included a Fun Fact (an intriguing fact related to the subject of the 
discovery) and a few selected references. More general references are listed at the back of 
the book. 

Following the 100 discovery entries, I have included three appendixes and a list of 
general references. The list of the 100 discoveries by their field of science (Appendix 1), an 
alphabetical list of all mentioned scientists (Appendix 2), and a list of “The Next 40” (Ap- 
pendix 3). This is a list of 40 important discoveries that just missed inclusion on my 100 
Greatest list and is an important source list for additional discoveries for students to re- 
search and discover for themselves. 


XV 



100 

Greatest 
Science 
Discoveries 
of All Time 




Levers and Buoyancy 

Year of Discovery: 260 B.C. 


What Is It? The two fundamental principles underlying all physics and 
engineering. 

Who Discovered It? Archimedes 


Why Is This One of the 100 Greatest? 

The concepts of buoyancy (water pushes up on an object with a force equal to the 
weight of water that the object displaces) and of levers (a force pushing down on one side of 
a lever creates a lifting force on the other side that is proportional to the lengths of the two 
sides of the lever) lie at the foundation of all quantitative science and engineering. They rep- 
resent humanity’s earliest breakthroughs in understanding the relationships in the physical 
world around us and in devising mathematical ways to describe the physical phenomena of 
the world. Countless engineering and scientific advances have depended on those two 
discoveries. 


How Was It Discovered? 

In 260 B.C. 26-year-old Archimedes studied the two known sciences — astronomy and 
geometry — in Syracuse, Sicily. One day Archimedes was distracted by four boys playing 
on the beach with a driftwood plank. They balanced the board over a waist-high rock. One 
boy straddled one end while his three friends jumped hard onto the other. The lone boy was 
tossed into the air. 

The boys slid the board off-center along their balancing rock so that only one-quarter 
of it remained on the short side. Three of the boys climbed onto the short, top end. The 
fourth boy bounded onto the rising long end, crashing it back down to the sand and catapult- 
ing his three friends into the air. 

Archimedes was fascinated. And he determined to understand the principles that so 
easily allowed a small weight (one boy) to lift a large weight (three boys). 

Archimedes used a strip of wood and small wooden blocks to model the boys and their 
driftwood. He made a triangular block to model their rock. By measuring as he balanced 
different combinations of weights on each end of the lever ( lever came from the Latin word 
meaning “to lift”), Archimedes realized that levers were an example of one of Euclid’s pro- 
portions at work. The force (weight) pushing down on each side of the lever had to be pro- 
portional to the lengths of board on each side of the balance point. He had discovered the 
mathematical concept of levers, the most common and basic lifting system ever devised. 

3 



4 Levers and Buoyancy 


Fifteen years later, in 245 B.C., Archimedes was ordered by King Hieron to find out 
whether a goldsmith had cheated the king. Hieron had given the smith a weight of gold and 
asked him to fashion a solid-gold crown. Even though the crown weighed exactly the same 
as the original gold, the king suspected that the goldsmith had wrapped a thin layer of gold 
around some other, cheaper metal inside. Archimedes was ordered to discover whether the 
crown was solid gold without damaging the crown itself. 

It seemed like an impossible task. In a public bathhouse Archimedes noticed his arm 
floating on the water’s surface. A vague idea began to form in his mind. He pulled his arm 
completely under the surface. Then he relaxed and it floated back up. 

He stood up in the tub. The water level dropped around the tub’s sides. He sat back 
down. The water level rose. 

He lay down. The water rose higher, and he realized that he felt lighter. He stood up. 
The water level fell and he felt heavier. Water had to be pushing up on his submerged body 
to make it feel lighter. 

He carried a stone and a block of wood of about the same size into the tub and submerged 
them both. The stone sank, but felt lighter. He had to push the wood down to submerge it. That 
meant that water pushed up with a force related to the amount of water displaced by the object 
(the object’s size) rather than to the object’s weight. How heavy the object felt in the water 
had to relate to the object’s density (how much each unit volume of it weighed). 

That showed Archimedes how to answer the king’s question. He returned to the king. 
The key was density. If the crown was made of some other metal than gold, it could weigh 
the same but would have a different density and thus occupy a different volume. 

The crown and an equal weight of gold were dunked into a bowl of water. The crown 
displaced more water and was thus shown to be a fake. 

More important, Archimedes discovered the principle of buoyancy: Water pushes up 
on objects with a force equal to the amount of water the objects displace. 


Allen, Pamela. Mr. Archimedes Bath. London: Gardeners Books, 1998. 

Bendick, Jeanne. Archimedes and the Door to Science. New York: Bethlehem Books, 1995. 

Gow, Mary. Archimedes: Mathematical Genius of the Ancient World. Berkeley 
Heights, NJ: Enslow Publishers, 2005. 

Heath, Tom. The Works of Archimedes: Edited in Modern Notation. Dover, DE: Ada- 
mant Media Corporation, 2005. 

Stein, Sherman. Archimedes: What Did He Do Besides Cry Eureka ? Washington, DC: 
The Mathematical Association of America, 1999. 

Zannos, Susan. The Life and Times of Archimedes. Hockessin, DE: Mitchell Lane Pub- 
lishers, 2004. 



Fun Facts: When Archimedes discovered the concept of buoyancy, he 
leapt form the bath and shouted the word he made famous: “Eureka!” 
which means “I found it!” That word became the motto of the state of Cali- 
fornia after the first gold rush miners shouted that they had found gold. 


More to Explore 


The Sun Is the Center 
of the Universe 


Year of Discovery: A.D. 1520 


What Is It? The sun is the center of the universe and the earth rotates around it. 
Who Discovered It? Nicholaus Copernicus 


Why Is This One of the 100 Greatest? 

Copernicus measured and observed the planets and stars. He gathered, compiled, and 
compared the observations of dozens of other astronomers. In so doing Copernicus chal- 
lenged a 2,000-year-old belief that the earth sat motionless at the center of the universe and 
that planets, sun, and stars rotated around it. His work represents the beginning point for our 
understanding of the universe around us and of modern astronomy. 

He was also the first to use scientific observation as the basis for the development of a 
scientific theory. (Before his time logic and thought had been the basis for theory.) In this 
way Copernicus launched both the field of modern astronomy and modern scientific 
methods. 


How Was It Discovered? 

In 1499 Copernicus graduated from the University of Bologna, Italy; was ordained a 
priest in the Catholic Church; and returned to Poland to work for his uncle, Bishop 
Waczenrode, at the Frauenburg Cathedral. Copernicus was given the top rooms in a cathe- 
dral tower so he could continue his astronomy measurements. 

At that time people still believed a model of the universe created by the Greek scientist, 
Ptolemy, more than 1,500 years earlier. According to Ptolemy, the earth was the center of 
the universe and never moved. The sun and planets revolved around the earth in great cir- 
cles, while the distant stars perched way out on the great spherical shell of space. But careful 
measurement of the movement of planets didn’t fit with Ptolomy’s model. 

So astronomers modified Ptolemy’s universe of circles by adding more circles within 
circles, or epi-circles. The model now claimed that each planet traveled along a small circle 
(epi-circle) that rolled along that planet’s big orbital circle around the earth. Century after 
century, the errors in even this model grew more and more evident. More epi-circles were 
added to the model so that planets moved along epi-circles within epi-circles. 


5 



6 The Sun Is the Center of the Universe 


Copernicus hoped to use “modern” (sixteenth-century) technology to improve on Ptol- 
emy’s measurements and, hopefully, eliminate some of the epi-circles. 

For almost 20 years Copernicus painstakingly measured the position of the planets 
each night. But his tables of findings still made no sense in Ptolemy’s model. 

Over the years, Copernicus began to wonder what the movement of the planets would 
look like from another moving planet. When his calculations based on this idea more accu- 
rately predicted the planets’ actual movements, he began to wonder what the motion of the 
planets would look like if the earth moved. Immediately, the logic of this notion became 
apparent. 

Each planet appeared at different distances from the earth at different times throughout 
a year. Copernicus realized that this meant Earth could not lie at the center of the planets’ 
circular paths. 

From 20 years of observations he knew that only the sun did not vary in apparent size 
over the course of a year. This meant that the distance from Earth to the sun had to always 
remain the same. If the earth was not at the center, then the sun had to be. Fie quickly calcu- 
lated that if he placed the sun at the universe’s center and had the earth orbit around it, he 
could completely eliminate all epi-circles and have the known planets travel in simple cir- 
cles around the sun. 

But would anyone believe Copernicus’s new model of the universe? The whole 
world — and especially the all-powerful Catholic Church — believed in an Earth-centered 
universe. 

For fear of retribution from the Church, Copernicus dared not release his findings dur- 
ing his lifetime. They were made public in 1543, and even then they were consistently 
scorned and ridiculed by the Church, astronomers, and universities alike. Finally, 60 years 
later, first Johannes Kepler and then Galileo Galilei proved that Copernicus was right. 


Crowe, Michael. Theories of the World from Antiquity to the Copernican Revolution. 
New York: Dover, 1994. 

Dreyer, J. A History of Astronomy from Thales to Kepler. New York: Dover, 1998 

Fradin, Dennis. Nicolaus Copernicus: The Earth Is a Planet. New York: Mondo Pub- 
lishing, 2004. 

Goble, Todd. Nicolaus Copernicus and the Founding of Modern Astornomy. Greens- 
boro, NC: Morgan Reynolds, 2003. 

Knight, David C. Copernicus: Titan of Modern Astronomy. New York: Franklin 
Watts, 1996 

Vollman, William. Uncentering the Earth: Copernicus and the Revolutions of the 
Heavenly Spheres. New York: W. W. Norton, 2006. 



\\ Fun Facts: Approximately one million Earths can fit inside the sun. But 
/ that is slowly changing. Some 4.5 pounds of sunlight hit the earth each 
I second. 


More to Explore 


Human Anatomy 

Year of Discovery: 1543 


What Is It? The first scientific, accurate guide to human anatomy. 
Who Discovered It? Andreas Vesalius 


Why Is This One of the 100 Greatest? 

The human anatomy references used by doctors through the year A.D. 1500 were 
actually based mostly on animal studies, more myth and error than truth. Andreas 
Vesalius was the first to insist on dissections, on exact physiological experiment and di- 
rect observation — scientific methods — to create his anatomy guides. His were the first 
reliable, accurate books on the structure and workings of the human body. 

Versalius’s work demolished the long-held reliance on the 1,500-year-old anatomical 
work by the early Greek, Galen, and marked a permanent turning point for medicine. For 
the first time, actual anatomical fact replaced conjecture as the basis for medical profession. 


How Was It Discovered? 

Andreas Vesalius was born in Brussels in 1515. His father, a doctor in the royal court, 
had collected an exceptional medical library. Young Vesalius poured over each volume and 
showed immense curiosity about the functioning of living things. He often caught and dis- 
sected small animals and insects. 

At age 1 8 Vesalius traveled to Paris to study medicine. Physical dissection of animal or 
human bodies was not a common part of accepted medical study. If a dissection had to be 
performed, professors lectured while a barber did the actual cutting. Anatomy was taught 
from the drawings and translated texts of Galen, a Greek doctor whose texts were written in 
50 B.C. 

Vesalius was quickly recognized as brilliant but arrogant and argumentative. During 
the second dissection he attended, Vesalius snatched the knife from the barber and demon- 
strated both his skill at dissection and his knowledge of anatomy, to the amazement of all in 
attendance. 

As a medical student, Vesalius became a ringleader, luring his fellow students to raid 
the boneyards of Paris for skeletons to study and graveyards for bodies to dissect. Vesalius 
regularly braved vicious guard dogs and the gruesome stench of Paris’s mound of 
Monfaucon (where the bodies of executed criminals were dumped) just to get his hands on 
freshly killed bodies to study. 


7 



8 Human Anatomy 


In 1537 Vesalius graduated and moved to the University of Padua (Italy), where he be- 
gan a long series of lectures — each centered on actual dissections and tissue experiments. 
Students and other professors flocked to his classes, fascinated by his skill and by the new 
reality he uncovered — muscles, arteries, nerves, veins, and even thin structures of the 
human brain. 

This series culminated in January 1540, with a lecture he presented to a packed theater 
in Bologna, Italy. Like all other medical students, Versalius had been trained to believe in 
Galen’s work. However, Vesalius had long been troubled because so many of his dissec- 
tions revealed actual structures that differed from Galen’s descriptions. 

In this lecture, for the first time in public, Vesalius revealed his evidence to discredit 
Galen and to show that Galen’s descriptions of curved human thighbones, heart chambers, 
segmented breast bones, etc., better matched the anatomy of apes than humans. In his lec- 
ture, Vesalius detailed more than 200 discrepancies between actual human anatomy and 
Galen’s descriptions. Time after time, Vesalius showed that what every doctor and surgeon 
in Europe relied on fit better with apes, dogs, and sheep than the human body. Galen, and 
every medical text based on his work, were wrong. 

Vesalius stunned the local medical community with this lecture. Then he secluded 
himself for three years preparing his detailed anatomy book. He used master artists to draw 
what he dissected — blood vessels, nerves, bones, organs, muscles, tendons, and brain. 

Vesalius completed and published his magnificent anatomy book in 1543. When med- 
ical professors (who had taught and believed in Galen their entire lives) received Vesalius’s 
book with skepticism and doubt, Vesalius flew into a rage and burned all of his notes and 
studies in a great bonfire, swearing that he would never again cut into human tissue. 

Luckily for us, his published book survived and became the standard anatomy text for 
over 300 years. 


O’Malley, C. Andreas Vesalius of Brussels. Novato, CA: Jeremy Norman Co., 1997. 

Persaud, T. Early History of Human Anatomy: From Antiquity to the Beginning of the 
Modern Era. London: Charles C. Thomas Publishers, 1995. 

Saunders, J. The Illustrations from the Works of Andreas Vesalius of Brussels. New 
York: Dover, 1993. 

Srebnik, Herbert. Concepts in Anatomy. New York: Springer, 2002. 

Tarshis, Jerome. Andreas Vesalius: Father of Modern Anatomy. New York: Dial 
Press, 1999. 



V Fun Facts: The average human brain weighs three pounds and contains 
/ 100 billion brain cells that connect with each other through 500 trillion 
I dendrites ! No wonder it was hard for Vesalius to see individual neurons. 


More to Explore 


Vesalius, Andreas. On the Fabric of the Human Body. Novato, CA: Jeremy Norman, 
1998. 


The Law of Falling 

Objects 


Year of Discovery: 1598 


What Is It? Objects fall at the same speed regardless of their weight. 
Who Discovered It? Galileo Galilei 


Why Is This One of the 100 Greatest? 

It seems a simple and obvious discovery. Heavier objects don’t fall faster. Why does it 
qualify as one of the great discoveries? Because it ended the practice of science based on the 
ancient Greek theories of Aristotle and Ptolemy and launched modern science. Galileo’s 
discovery brought physics into the Renaissance and the modem age. It laid the foundation 
for Newton’s discoveries of universal gravitation and his laws of motion. Galileo’s work 
was an essential building block of modern physics and engineering. 


How Was It Discovered? 

Galileo Galilei, a 24-year-old mathematics professor at the University of Pisa, Italy, 
often sat in a local cathedral when some nagging problem weighed on his mind. Lamps 
gently swung on long chains to illuminate the cathedral. One day in the summer of 1598, 
Galileo realized that those lamps always swung at the same speed. 

He decided to time them. He used the pulse in his neck to measure the period of each 
swing of one of the lamps. Then he timed a larger lamp and found that it swung at the same 
rate. He borrowed one of the long tapers alter boys used to light the lamps and swung both 
large and small lamps more vigorously. Over many days he timed the lamps and found that 
they always took exactly the same amount of time to travel through one complete arc. It 
didn’t matter how big (heavy) the lamp was or how big the arc was. 

Heavy lamps fell through their arc at the same rate as lighter lamps. Galileo was fasci- 
nated. This observation contradicted a 2,000-year-old cornerstone of beliefs about the 
world. 

He stood before his class at the University of Pisa, Italy, holding bricks as if weighing 
and comparing them — a single brick in one hand and two bricks that he had cemented to- 
gether in the other. “Gentlemen, I have been watching pendulums swing back and forth. 
And I have come to a conclusion. Aristotle is wrong.” 


9 



10 The Law of Falling Objects 


The class gasped, “Aristotle? Wrong?!” The first fact every schoolboy learned in be- 
ginning science was that the writings of the ancient Greek philosopher, Aristotle, were the 
foundation of science. One of Aristotle’s central theorems stated that heavier objects fall 
faster because they weigh more. 

Galileo climbed onto his desk, held the bricks at eye level, and let them fall. Thud! 
Both bricks crashed to the floor. “Did the heavier brick fall faster?” he demanded. 

The class shook their heads. No, it had not. They landed together. 

“Again!” cried Galileo. His students were transfixed as Galileo again dropped the 
bricks. Crash! “Did the heavy brick fall faster?” No, again the bricks landed together. “Aris- 
totle is wrong,” declared their teacher to a stunned circle of students. 

But the world was reluctant to hear Galileo’s truth. On seeing Galileo’s brick demon- 
stration, friend and fellow mathematician Ostilio Ricci admitted only that “This double 
brick falls at the same rate as this single brick. Still, I cannot so easily believe Aristotle is 
wholly wrong. Search for another explanation.” 

Galileo decided that he needed a more dramatic, irrefutable, and public demonstration. 
It is believed (though not substantiated) that, for this demonstration, Galileo dropped a 
ten-pound and a one-pound cannonball 191 feet from the top of the famed Leaning Tower 
of Pisa. Whether he actually dropped the cannonballs or not, the science discovery had been 
made. 


(f~^\ Fun Facts: Speaking of falling objects, the highest speed ever reached 
by a woman in a speed skydiving competition is 432. 12 kph (268.5 mph). 

Cl Italian daredevil Lucia Bottari achieved this record-breaking velocity 
above Bottens, Switzerland, on September 16, 2002, during the annual 
Speed Skydiving World Cup. 

More to Explore 

Aldrain, Buzz. Galileo for Kids: His Life and Ideas. Chicago: Chicago Review Press, 
2005. 

Atkins, Peter, Galileo’s Finger: The Ten Great Ideas of Science. New York: Random 
House, 2004. 

Bendick, Jeanne. Along Came Galileo. San Luis Obispo, CA: Beautiful Feet Books, 
1999. 

Drake, Stillman. Galileo. New York: Hill and Wang, 1995. 

Fisher, Leonard. Galileo. New York: Macmillan, 1998. 

Galilei, Galileo. Galileo on the World Systems: A New Abridged Translation and 
Guide. Berkeley: University of California Press, 1997. 

MacHamer, Oeter, ed. The Cambridge Companion to Galileo. New York: Cambridge 
University Press, 1998. 

MacLachlan, James. Galileo Galilei: First Physicist. New York: Oxford University 
Press, 1997. 

Sobel, Dava. Galileo’s Daughter. New York: Walker & Co., 1999. 


Planetary Motion 

Year of Discovery: 1609 


What Is It? The planets orbit the sun not in perfect circles, but in ellipses. 
Who Discovered It? Johannes Kepler 


Why Is This One of the 100 Greatest? 

Even after Copernicus simplified and corrected the structure of the solar system by dis- 
covering that the sun, not the earth, lay at the center of it, he (like all astronomers before 
him) assumed that the planets orbited the sun in perfect circles. As a result, errors continued 
to exist in the predicted position of the planets. 

Kepler discovered the concept of the ellipse and proved that planets actually follow 
slightly elliptical orbits. With this discovery, science was finally presented with an accurate 
pictures of the position and mechanics of the solar system. After 400 years of vastly 
improved technology, our image of how planets move is still the one Kepler created. We 
haven’t changed or corrected it one bit, and likely never will. 


How Was It Discovered? 

For 2,000 years, astronomers placed the earth at the center of the universe and assumed 
that all heavenly bodies moved in perfect circles around it. But predictions using this system 
never matched actual measurements. Scientists invented epi-circles — small circles that the 
planets actually rolled around that, themselves, rolled around the great circular orbits for 
each planet. Still there were errors, so scientists created epi-circles on the epi-circles. 

Copernicus discovered that the sun lay at the center of the solar system, but still as- 
sumed that all planets traveled in perfect circles. Most epi-circles were eliminated, but er- 
rors in planetary plotting continued. 

Johannes Kepler was born in Southern Germany in 1571, 28 years after the release of 
Copernicus’s discovery. Kepler suffered through a troubled upbringing. His aunt was 
burned at the stake as a witch. His mother almost suffered the same fate. The boy was often 
sick and had bad eyesight that glasses could not correct. Still, Kepler enjoyed a brilliant — 
but again troubled — university career. 

In 1597 he took a position as an assistant to Tycho Brahe, famed German astronomer. 
For decades Tycho had been measuring the position of the planets (especially Mars) with 
far greater precision than any other European astronomer. When Tycho died in 1601 he left 
all his notes and tables of planetary readings to Kepler. 


11 



12 Planetary Motion 


Kepler rejected the epi-circle on epi-circle model of how planets moved and decided to 
work out an orbit for Mars that best fit Tycho’s data. It was still dangerous to suggest that 
the sun lay at the center of the solar system. The all-powerful Catholic Church had burned 
Friar Giordano Bruno at the stake for believing Copernicus. No other scientist had dared 
come forth to support Copernicus’s radical notion. Still, Kepler was determined to use Co- 
pernicus’s organization for the universe and Tycho’s data to make sense of the planets. 

Kepler tried many ideas and mathematical approaches that didn’t work. His bad eye- 
sight prevented him from making his own astronomical sightings. He was forced to rely en- 
tirely on Tycho’s existing measurements. In bitter frustration, he was finally driven to 
consider what was — at the time — unthinkable: planetary orbits that weren’t perfect circles. 
Nothing else explained Tycho’s readings for Mars. 

Kepler found that ellipses (elongated circles) fit far better with the accumulated read- 
ings. Yet the data still didn’t fit. In desperation, Kepler was forced to consider something 
else that was also unthinkable at that time: maybe the planets didn’t orbit the sun at a 
constant speed. 

With these two revolutionary ideas Kepler found that elliptical orbits fit perfectly with 
Tycho’s measured planetary motion. Elliptical orbits became Kepler’s first law. Kepler 
then added his Second Law: each planet’s speed altered as a function of its distance from the 
sun. As a planet flew closer, it flew faster. 

Kepler published his discoveries in 1609 and then spent the next 18 years calculating 
detailed tables of planetary motion and position for all six known planets. This was also the 
first practical use of logarithms, invented by Scotsman John Napier during the early years of 
Kepler’s effort. With these tables of calculations (which exactly matched measured plane- 
tary positions) Kepler proved that he had discovered true planetary motion. 

Fun Facts: Pluto was called the ninth planet for 75 years, since its dis- 
vLy covery in 1930. Pluto’s orbit is the least circular (most elliptical) of all 
H planets. At its farthest, it is 7.4 billion km from the sun. At its nearest it is 
only 4.34 billion km away. When Pluto is at its closest, its orbit actually 
slips inside that of Neptune. For 20 years out of every 248, Pluto is actu- 
ally closer to the sun than Neptune is. That occurred from 1979 to 1999. 
For those 20 years Pluto was actually the eighth planet in our solar sys- 
tem and Neptune was the ninth! 

More to Explore 

Casper, Max. Kepler. New York: Dover, 1993. 

Dreyer, J. A History of Astronomy from Thales to Kepler. New York: Dover, 1993. 

Huff, Toby. The Rise of Early Modern Science. New York: Cambridge University 
Press, 1993. 

North, John. The Norton History of Astronomy and Cosmology. New York: Norton, 
1995. 

Stephenson, Bruce. Kepler’s Physical Astronomy. Princeton, NJ: Princeton University 
Press, 1997. 


Jupiter’s Moons 


Year of Discovery: 1610 


What Is It? Other planets (besides Earth) have moons. 
Who Discovered It? Galileo Galilei 


Why Is This One of the 100 Greatest? 

Galileo discovered that other planets have moons and thus extended human understand- 
ing beyond our own planet. His careful work with the telescopes he built launched modern as- 
tronomy. His discoveries were the first astronomical discoveries using the telescope. 

Galileo proved that Earth is not unique among planets of the universe. He turned 
specks of light in the night sky into fascinating spherical objects — into places — rather than 
pinpricks of light. In so doing, he proved that Polish astronomer Nicholaus Copernicus had 
been right when he claimed that the sun was the center of the solar system. 

With his simple telescope Galileo single-handedly brought the solar system, galaxy, 
and greater universe within our grasp. His telescope provided vistas and understanding that 
did not exist before and could not exist without the telescope. 


How Was It Discovered? 

This was a discovery made possible by an invention — the telescope. Galileo saw his first 
telescope in late 1608 and instantly recognized that a more powerful telescope could be the an- 
swer to the prayers of every astronomer. By late 1609 Galileo had produced a 40-power, 
two-lens telescope. That 1609 telescope was the first practical telescope for scientific use. 

A paper by Johannes Kepler describing the orbits of the planets convinced Galileo to 
believe the theory of Polish astronomer Nicholaus Copernicus, who first claimed that the 
sun was the center of the universe, not the earth. Believing Copernicus was a dangerous 
thing to do. Friar Giordano Bruno had been burned at the stake for believing Copernicus. 
Galileo decided to use his new telescope to prove that Copernicus was right by more accu- 
rately charting the motion of the planets. 

Galileo first turned his telescope on the moon. There he clearly saw mountains and val- 
leys. He saw deep craters with tall, jagged rims slicing like serrated knives into the lunar 
sky. The moon that Galileo saw was radically different from the perfectly smooth sphere 
that Aristotle and Ptolemy said it was (the two Greek astronomers whose teachings still 
formed the basis of all science in 1610). Both the all-powerful Catholic Church and every 
university and scientist in Europe believed Aristotle and Ptolemy. 


13 



14 Jupiter’s Moons 


In one night’ s viewing of the moon’ s surface through his telescope, Galileo proved Ar- 
istotle wrong — again. The last time Galileo’s observations had contradicted Aristotle’s 
teachings, Galileo had been fired from his teaching position for being right when he proved 
that all objects fall at the same rate regardless of their weight. 

Galileo next aimed his telescope at Jupiter, the biggest planet, planning to carefully 
chart its motion over several months. Through his telescope (the name is a combination of 
the Greek words for “distant” and “looking”) Galileo saw a magnified view of the heavens 
no human eye had ever seen. He saw Jupiter clearly, and, to his amazement, he found moons 
circling the giant planet. Aristotle had said (and all scientists believed) that Earth was the 
only planet in the universe that had a moon. Within days, Galileo discovered four of Jupi- 
ter’s moons. These were the first discovered moons other than our own. 

Aristotle was wrong again. 

Still, old beliefs do not die easily. In 1616 the Council of Cardinals forbade Galileo 
ever again to teach or promote Copernicus’s theories. Many senior church officials refused 
to look through a telescope, claiming it was a magician’s trick and that the moons were in 
the telescope. 

When Galileo ignored their warning, he was summoned to Rome by the Church’s 
all-powerful Inquisition. A grueling trial followed. Galileo was condemned by the Church 
and forced to publicly recant his views and findings. He was placed under house arrest for 
the rest of his life, dying in 1640 without hearing even one voice other than his own pro- 
claim that his discoveries were true. The Church did not rescind the condemnation of Gali- 
leo and his discoveries until October 1992, 376 years after they incorrectly condemned him. 


Aldrain, Buzz. Galileo for Kids: His Life and Ideas. Chicago: Chicago Review Press, 2005. 

Atkins, Peter, Galileo’s Finger: the Ten Great Ideas of Science. New York: Random 
House, 2004. 

Bendick, Jeanne. Along Came Galileo. San Luis Obispo, CA: Beautiful Feet Books, 1999. 
Drake, Stillman. Galileo. New York: Hill and Wang, 1995. 

Fisher, Leonard. Galileo. New York: Macmillan, 1998. 

Galilei, Galileo. Galileo on the World Systems: A New Abridged Translation and 
Guide. Berkeley: University of California Press, 1997. 

MacHamer, Oeter, ed. The Cambridge Companion to Galileo. New York: Cambridge 
University Press, 1998. 

MacLachlan, James. Galileo Galilei: First Physicist. New York: Oxford University 
Press, 1997. 

Sobel, Dava. Galileo’s Daughter. New York: Walker & Co., 1999. 



Ti Fun Facts: Galileo would have been astonished to learn that Jupiter re- 
/ sembles a star in composition. In fact, if it had been about 80 times more 
' massive, it would have been classified as a star rather than a planet. 


More to Explore 


Human Circulatory System 

Year of Discovery: 1628 


What Is It? The first complete understanding of how arteries, veins, heart, and 
lungs function to form a single, complete circulatory system. 

Who Discovered It? William Harvey 


Why Is This One of the 100 Greatest? 

The human circulatory system represents the virtual definition of life. No system is 
more critical to our existence. Yet only 400 years ago, no one understood our circulatory 
system. Many seriously thought that the thumping inside the chest was the voice of the con- 
science trying to be heard. Most thought that blood was created in the liver and consumed 
by the muscles. Some still thought that arteries were filled with air. 

William Harvey discovered the actual function of the major elements of the circulatory 
system (heart, lungs, arteries, and veins) and created the first complete and accurate picture 
of human blood circulation. Harvey was also the first to use the scientific method for bio- 
logical studies. Every scientist since has followed his example. Harvey’s 1628 book repre- 
sents the beginning of modem physiology. 


How Was It Discovered? 

Through the sixteenth century, doctors relied on the 1,500-year-old writings of the 
Greek physician Galen, who said that food was converted into blood in the liver and was 
then consumed by the body for fuel. Most agreed that the blood that flowed through arteries 
had no connection with the blood that flowed through veins. 

William Harvey was bom in 1578 in England and received medical training at Oxford. 
He was invited to study at Padua University in Italy, the acknowledged medical center of 
Europe. 

When Harvey returned to England in 1602, he married the daughter of Queen Eliza- 
beth’s doctor, was appointed a physician in the court of King James I, and was then ap- 
pointed personal physician to King Charles I in 1618. 

While serving the English kings, Harvey focused his studies on veins and arteries. He 
conducted extensive experiments with animals and human corpses. During these dissec- 
tions, he discovered the series of flap valves that exist throughout the veins. He was not the 
first to find these valves, but he was the first to note that they always directed blood flow to- 
ward the heart. Blood flowed in veins only from the arms, legs, and head back to the heart. 


15 



16 Human Circulatory System 


He began a series of animal experiments in which he tied off a single artery or vein to 
see what happened. Sometimes he clamped an artery and later released it to see where this 
surge of blood would go. He did the same with veins, clamping a vein and then releasing it. 
Sometimes he clamped both vein and artery and then released one at a time. These experi- 
ments proved that arteries and veins were connected into a single circulatory system and 
that blood always flowed from arteries to veins. 

Harvey turned to the heart itself and soon realized that the heart acted as a muscle and 
pushed blood out to lungs and out into arteries. Following blood as it flowed through vari- 
ous animals, Harvey saw that blood was not consumed, but circulated over and over again 
through the system, carrying air and nourishment to the body. 

By 1625 Harvey had discovered an almost complete picture of the circulatory system. 
He faced two problems. First, he couldn’t figure out how blood got from an artery across to 
a vein, even though his experiments proved that it did. (Harvey had no microscope and so 
couldn’t see blood vessels as small as capillaries. By 1670 — three years after Harvey’s 
death — Italian Marcello Malpighi had discovered capillaries with a microscope, thus com- 
pleting Harvey’s circulatory system.) 

The second problem Harvey faced was his fear of mob reactions, Church condemna- 
tion when he said that the heart was just a muscular pump and not the house of the soul and 
consciousness, and the press (scribes). He was afraid he’d lose his job with the king. In 1628 
Harvey found a small German publisher to publish a thin (72-page) summary of his work 
and discoveries. He published it in Latin (the language of science), hoping no one in Eng- 
land would read it. 

News of Harvey’ s book raced across Europe and made him instantly notorious. He lost 
many patients, who were shocked by his claims. But Harvey’s science was careful and ac- 
curate. By 1650 Harvey’s book had become the accepted textbook on the circulatory 
system. 


Curtis, R. Great Lives: Medicine. New York: Charles Scribner’s Sons Books for 
Young Readers, 1993. 

Harvey, William. On the Motion of the Heart and Blood in Animals. Whitefish, MT: 
Kessinger Publishing, 2005. 

Power, D’Arcy. William Harvey: Master of Medicine. Whitefish, MT: Kessinger, 
2005. 

Shackleford, Joel. William Harvey and the Mechanics of the Heart. New York: Oxford 
University Press, 2003. 

Wyatt, Hervey. William Harvey: 1578 to 1657. Whitefish, MT: Kessinger, 2005. 

Yount, Lisa. William Harvey: Discoverer of How Blood Circulates. Berkeley Heights, 
NJ: Enslow, 1998. 



A Fun Facts: Americans donate over 16 million pints of blood each year. 
) That’s enough blood to fill a swimming pool 20 feet wide, 8 feet deep, 
* and one-third of a mile long! 


More to Explore 


Air Pressure 


Year of Discovery: 1640 


What Is It? Air (the atmosphere) has weight and presses down on us. 
Who Discovered It? Evangelista Torricelli 


Why Is This One of the 100 Greatest? 

It is a simple, seemingly obvious notion: air has weight; the atmosphere presses down 
on us with a real force. However, humans don’t feel that weight. You aren’t aware of it be- 
cause it has always been part of your world. The same was true for early scientists, who 
never thought to consider the weight of air and atmosphere. 

Evangelista Torricelli’s discovery began the serious study of weather and the atmo- 
sphere. It launched our understanding of the atmosphere. This discovery helped lay the 
foundation for Newton and others to develop an understanding of gravity. 

This same revelation also led Torricelli to discover the concept of a vacuum and to in- 
vent the barometer — the most basic, fundamental instrument of weather study. 


How Was It Discovered? 

On a clear October day in 1640, Galileo conducted a suction-pump experiment at a 
public well just off the market plaza in Florence, Italy. The famed Italian scientist lowered a 
long tube into the well’s murky water. From the well, Galileo’s tube draped up over a 
wooden cross-beam three meters above the well’s wall, and then down to a hand-powered 
pump held by two assistants: Evangelista Torricelli, the 32-year-old the son of a wealthy 
merchant and an aspiring scientist, and Giovanni Baliani, another Italian physicist. 

Torricelli and Baliani pumped the pump’s wooden handlebar, slowly sucking air out 
of Galileo’s tube, pulling water higher into the tube. They pumped until the tube flattened 
like a run-over drinking straw. But no matter how hard they worked, water would not rise 
more than 9.7 meters above the well’s water level. It was the same in every test. 

Galileo proposed that — somehow — the weight of the water column made it collapse 
back to that height. 

In 1643, Torricelli returned to the suction pump mystery. If Galileo was correct, a 
heavier liquid should reach the same critical weight and collapse at a lower height. Liquid 
mercury weighted 13.5 times as much as water. Thus, a column of mercury should never 
rise any higher than 1/13.5 the height of a water column, or about 30 inches. 


17 



18 Air Pressure 


Torricelli filled a six-foot glass tube with liquid mercury and shoved a cork into the 
open end. Then he inverted the tube and submerged the corked end in a tub of liquid mer- 
cury before he pulled out the stopper. As he expected, mercury flowed out of the tube and 
into the tub. But not all of the mercury ran out. 

Torricelli measured the height of the remaining mercury column — 30 inches, as ex- 
pected. Still, Torricelli suspected that the mystery’s true answer had something to do with 
the vacuum he had created above his column of mercury. 

The next day, with wind and a cold rain lashing at the windows, Torricelli repeated his 
experiment, planning to study the vacuum above the mercury. However, on this day the 
mercury column only rose to a height of 29 inches. 

Torricelli was perplexed. He had expected the mercury to rise to the same height as 
yesterday. What was different? Rain beat on the windows as Torricelli pondered this new 
wrinkle. 

What was different was the atmosphere, the weather. Torricelli’s mind latched onto a 
revolutionary new idea. Air, itself, had weight. The real answer to the suction pump mys- 
tery lay not in the weight of the liquid, nor in the vacuum above it, but in the weight of the at- 
mosphere pushing down around it. 

Torricelli realized that the weight of the air in the atmosphere pushed down on the mer- 
cury in the tub. That pressure forced mercury up into the tube. The weight of the mercury in 
the tube had to be exactly equal to the weight of the atmosphere pushing down on the mer- 
cury in the tub. 

When the weight of the atmosphere changed, it would push down either a little bit 
more or a little bit less on the mercury in the tub and drive the column of mercury in the tube 
either a little higher or a little lower. Changing weather must change the weight of the atmo- 
sphere. 

Torricelli had discovered atmospheric pressure and a way to measure and study it. 


Asimov, Isaac. Asimov’s Chronology of Science and Discovery. New York: Haiper & 
Row, 1989. 

Clark, Donald. Encyclopedia of Great Inventors and Discoveries. London: Marshall 
Cavendish Books, 1991. 

Haven, Kendall. Marvels of Science. Englewood, CO: Libraries Unlimited, 1994. 

Macus, Rebecca. Galileo and Experimental Science. New York: Franklin Watts, 1991. 

Middleton, W. E. The History of the Barometer. New Brunswick, NJ: Johns Hopkins 
University Press, 2003. 



Fun Facts: Home barometers rarely drop more than 0.5 inch of mercury 
as the weather changes from fair to stormy. The greatest pressure drop 
ever recorded was 2.963 inches of mercury, measured inside a South Da- 
kota tornado in June 2003. 


More to Explore 


Boyle’s Law 

Year of Discovery: 1650 


What Is It? The volume of a gas is inversely proportional to the force squeez- 
ing it. 

Who Discovered It? Robert Boyle 


Why Is This One of the 100 Greatest? 

The concept Robert Boyle discovered (now called Boyle’s Law) laid the foundation 
for all quantitative study and chemical analysis of gasses. It was the first quantitative for- 
mula to describe the behavior of gasses. Boyle’s Law is so basic to understanding chemistry 
that it is taught to every student in beginning chemistry classes. 

A genius experimenter, Boyle also proved that gasses were made of atoms — just like 
solids. But in a gas, the atoms are spread far apart and disconnected so that they can be 
squeezed tighter. Through these experiments Boyle helped convince the scientific world 
that atoms existed — an issue still debated 2,000 years after their existence was first pro- 
posed by Democritus in 440 B.C. 


How Was It Discovered? 

Robert Boyle was the son of an earl and a member of the British Scientific Society. 
During a 1662 society meeting, Robert Hooke read a paper describing a French experiment 
on the “springiness of air.” The characteristics of air were of great interest to scientists in the 
seventeenth century. 

French scientists built a brass cylinder fitted tightly with a piston. Several men pushed 
down hard on the piston, compressing the air trapped below. Then they let go. The piston 
sprang back up, but not all the way back up. No matter how often the French tried this ex- 
periment, the piston never bounced all the way back up. 

The French claimed this proved that air was not perfectly springy. Once compressed, it 
stayed slightly compressed. 

Robert Boyle claimed that the French experiment proved nothing. Their piston, he 
said, was too tight to bounce all the way back up. Others argued that, if they made the piston 
looser, air would leak around the edges and ruin the experiment. 

Boyle promised to create a perfect piston that was neither too tight nor too loose. He 
also claimed that his perfect piston would prove the French wrong. 


19 



20 Boyle’s Law 


Two weeks later Robert Boyle stood before the society with a large glass tube that he 
had shaped into a lopsided “U.” One side of the “U” rose over three feet high and was 
skinny. The other side was short and fat. The short side was sealed at the top. The tall, 
skinny side was open. 

Boyle poured liquid mercury into his tube until it covered the bottom of the “U” and 
rose just a little in both sides. A large pocket of air was trapped above this mercury in the 
short fat side. A piston, Boyle explained, was any devise that compressed air. Since his used 
mercury to compress air, there would be no friction to affect the results — as had been true in 
the French experiment. 

Boyle recorded the glass piston’s weight and etched a line in the glass where mercury 
met the trapped air pocket. Boyle trickled liquid mercury down the long neck of the tall side 
of his piston until he had filled the neck. Mercury now rose well over halfway up the short 
side. The trapped air had been squeezed to less than half of its original volume by the weight 
and force of mercury. 

Boyle drew a second line on the short chamber to mark the new level of mercury 
inside — marking the compressed volume of trapped air. 

He then drained mercury through a valve at the bottom of the “U” until the glass piston 
and mercury weighed exactly the same as they had at the beginning. The mercury level re- 
turned to its exact starting line. The trapped air had sprung back exactly to where it started. 
Air was perfectly springy. The French were wrong. Boyle was right. 

Robert Boyle continued the experiments with his funny glass piston and noticed some- 
thing quite remarkable. When he doubled the pressure (weight of mercury) on a trapped 
body of air, he halved its volume. When he tripled the pressure, the air’ s volume was re- 
duced to one-third. The change in volume of air when compressed was always proportional 
to the change in the pressure squeezing that air. He created a simple mathematical equation 
to describe this proportionality. Today we call it “Boyle’s Law.” No other concept has been 
more useful in understanding and using gasses to serve the needs of humankind. 


Boyle, Robert. The Skeptical Chemist. New York: Dover, 2003. 

Hall, Marie. Robert Boyle on Natural Philosophy. Bloomington: Indiana University 
Press, 1995. 

Hunter, Michael. Robert Boyle Reconsidered. New York: Cambridge University 
Press, 2003. 

Irwin, Keith. The Romance of Chemistry. New York: Viking Press, 1996. 

Tiner, John. Robert Boyle: Trailblazer of Science. Fenton, MI: Mott Media, 1999. 

Wojcik, Jan. Robert Boyle and the Limits of Reason. New York: Cambridge Univer- 
sity Press, 2003. 



Fun Facts: Oceanographer Sylvia Earle set the women’s depth record 
for solo diving (1,000 meters or 3,281 feet). According to the concept 
Boyle discovered, pressure at that depth is over 100 times what it is at the 
surface ! 


More to Explore 


The Existence of Cells 


Year of Discovery: 1665 


What Is It? The cell is the basic building block of all living organisms. 
Who Discovered It? Robert Hooke 


Why Is This One of the 100 Greatest? 

The cell is the basic unit of anatomy. Countless millions of cells build living plants and 
animals. The functions of a body can be studied by studying individual cells. Just as the dis- 
covery of the molecule and atom allowed scientists to better understand chemical sub- 
stances, Hooke’s discovery of the cell has allowed biologists to better understand living 
organisms. 

Hooke’s work with a microscope opened the public’s eyes to the microscopic world 
just as Galileo’s work with the telescope opened their eyes to a vast and wondrous universe. 
Hooke’s work and discoveries mark the moment when microscopy came of age as a scien- 
tific discipline. 


How Was It Discovered? 

Robert Hooke was a most interesting fellow. Weak and sickly as a child, Hooke’s par- 
ents never bothered to educate him because they didn’t think he would survive. When 
Hooke was still alive at age 1 1 , his father began a halfhearted, homeschool education. When 
Hooke was 12, he watched a portrait painter at work and decided, “I can do that.” Some ini- 
tial sketches showed that he was good at it. 

The next year Hooke’s father died, leaving Hooke a paltry inheritance of only £100. 
Hooke decided to use the money to apprentice himself to a painter, but quickly learned that 
the paint fumes gave him terrible headaches. 

He used his money instead to enter Westminster school. On one of his first days there, 
Hooke listened to a man play the school organ and thought, “I can do that.” Hooke soon 
proved that he was good at it and learned both to play and to serve as a choirmaster. 

Unfortunately, the new English puritanical government banned such frivolity as 
church choirs and music. Hook’s money had been wasted. Not knowing what else to do, 
Hooke hired himself out as a servant to rich science students at nearby Oxford University. 
Hooke was fascinated with science and again thought, “I can do that.” As it turns out, he 
was exceptionally good at it. His servitude at Oxford (mostly to Robert Boyle) was the start 
of one of the most productive science careers in English history. Hooke soon developed an 
excellent reputation as a builder and as an experimenter. 

21 



22 The Existence of Cells 


Microscopes were invented in the late 1590s. By 1660 only a few had been built that 
were able to magnify objects 100 times normal size. As microscopes became more power- 
ful, they maintained focus on only a tiny sliver of space and were increasingly more difficult 
to focus and to use. 

Hooke was hired onto the staff of the Royal Society (an early English scientific organi- 
zation) in 1660 and soon began a long series of microscopic studies. By 1662 he had helped 
design a 300-power microscope, which he used to examine the microscopic structure of 
common objects. Using this microscope and his artistic talent, Hooke created the first de- 
tailed studies of the microscopic world, rendering with lifelike accuracy the contours of a 
fly’s compound eyes, the structure of a feather, and a butterfly’s wing. He also drew and 
identified a series of microscopic bugs. 

In 1664 Hooke turned his microscope onto a thin sheet of dried cork and found it to be 
composed of a tightly packed pattern of tiny rectangular holes. Actually, cork has large, 
open cells. That’s why Hooke was able to see them at all. The cells of other plants and ani- 
mal tissue he studied were all too small to be seen through his microscopes. 

Hooke called these holes cells (the Latin word for small chambers that stand in a 
row — as in prison cells). These cells were empty because the cork was dead. Hooke cor- 
rectly suspected that, while living, these had been filled with fluid. 

The name “cell” stuck. More important, the concept galvanized biologists. The living 
world was constructed of countless tiny cells stacked together like bricks in a wall. The en- 
tire field of biology shifted toward a study of cell structure and cell function. 


Dyson, James. A History of Great Inventions. New York: Carroll & Graf Publishers, 


Headstrom, Richard. Adventures with a Microscope. Mineola, NY: Dover Publica- 
tions, 1997. 

Inwood, Stephen. The Forgotten Genius: The Biography of Robert Hooke. San Fran- 
cisco: MacAdam/Cage Publishing, 2005. 

Jardine, Lisa. The Curious Life of Robert Hooke. New York: HarperPerennial, 2005. 
Oxlade, Chris. The World of Microscopes. New York: Usborne Books, 1999. 

Suplee, Curt. Milestones of Science. Washington, DC: National Geographic Society, 



Fun Facts: Cell biology is the only science in which multiplication 
/ means the same thing as division. 


More to Explore 


2001 . 


2000 . 


Yenne, Bill. 1 00 Inventions That Shaped World History. New York: Bluewood Books, 
1998. 


Universal Gravitation 

Year of Discovery: 1666 


What Is It? Gravity is the attractive force exerted by all objects on all other 
objects. 

Who Discovered It? Isaac Newton 


Why Is This One of the 100 Greatest? 

By the early seventeenth century, many forces had been identified: friction, gravity, air 
resistance, electrical, forces people exerted, etc. Newton’s mathematical concept of gravity 
was the first step in joining these seemingly different forces into a single, unified concept. 
An apple fell; people had weight; the moon orbited Earth — all for the same reason. New- 
ton’s law of gravity was a giant, simplifying concept. 

Newton’s concept of, and equations for, gravity stand as one of the most used concepts 
in all science. Most of our physics has been built upon Newton’ s concept of universal gravi- 
tation and his idea that gravity is a fundamental property of all matter. 


How Was It Discovered? 

In 1666, Isaac Newton was a 23-year-old junior fellow at Trinity College in Cam- 
bridge. With his fair complexion and long blond hair, many thought he still looked more 
like a boy. His small, thin stature and shy, sober ways reinforced that impression. His in- 
tense eyes and seemingly permanent scowl pushed people away. 

In London, the bubonic plague ravaged a terrified population. Universities were 
closed, and eager academics like Isaac Newton had to bide their time in safe country estates 
waiting for the plague to loosen its death grip on the city. It was a frightening time. 

In his isolation, Newton was obsessed with a question: What held the moon circling 
the earth, and what held the earth in a captive orbit around the sun? Why didn’t the moon 
fall down to the earth? Why didn’t the earth fall down to the sun? 

In later years Newton swore that this story actually happened. As he sat in the orchard 
at his sister’s estate, he heard the familiar soft “thunk” of an apple falling to the grass-car- 
peted ground, and turned in time to see a second apple fall from an overhanging branch and 
bounce once before settling gently into the spring grass. It was certainly not the first apple 
Isaac Newton had ever seen fall to the ground, nor was there anything at all unusual about 
its short fall. However, while it offered no answers to the perplexed young scientist, the fall- 
ing apple did present Isaac with an important new question, “The apple falls to Earth while 
the moon does not. What’s the difference between the apple and the moon?” 

23 



24 Universal Gravitation 


Next morning, under a clearing sky, Newton saw his young nephew playing with a 
ball. The ball was tied to a string the boy held tight in his fist. He swung the ball, slowly at 
first, and then faster and faster until it stretched straight out. 

With a start Newton realized that the ball was exactly like the moon. Two forces acted 
on the ball — its motion (driving it outward) and the pull of a string (holding it in). Two 
forces acted on the moon. Its motion and the pull of gravity — the same pull (force) that 
made the apple fall. 

For the first time, Newton considered the possibility that gravity was a universal at- 
tractive force instead of a force that applied only to planets and stars. His deep belief in al- 
chemy and its concept of the attraction of matter led him to postulate that gravitational 
attraction force did not just apply to heavenly objects, but to all objects with any mass. 
Gravity pulled apples to earth, made rain fall, and held planets in their orbits around the sun. 

Newton’s discovery of the concept of universal gravitation was a major blow to the 
prevalent belief that the laws of nature on Earth were different from those that ruled the 
heavens. Newton showed that the machinery that ruled the universe and nature is simple. 

Newton developed universal gravitation as a property of all matter, not just of planets 
and stars. Universal gravitation and its mathematical expression lie at the foundation of all 
modern physics as one of the most important principles in all science. 


Christianson, Gale. Isaac Newton and the Scientific Revolution. New York: Oxford 
University Press, 1996. 

Gale, Christeanson. In the Presence of the Creator: Isaac Newton and His Times. New 
York: Collier Macmillan, 1994. 

Gleick, James. Isaac Newton. New York: Vintage , 2004 

Koestler, Arthur. The Sleepwalkers: A History of Man’s Changing Vision of the Uni- 
verse. London: Hutchinson & Co., 1999. 

Maury, Jean. Newton: The Father of Modern Astronomy. New York: Harry Abrams, 
1996. 

Peteson, Ivars. Newton’s Clock. New York: W. H. Freeman, 1995. 

White, Michael. Isaac Newton: The Last Sorcerer. Jackson, TN: Perseus Books, 1999. 



\\ Fun Facts: The Flower of Kent is a large green variety of apple. Accord- 
/ ing to the story, this is the apple Isaac Newton saw falling to ground from 
' its tree, inspiring his discovery of universal gravitation. 


More to Explore 


Year of Discovery: 1669 


Fossils 


What Is It? Fossils are the remains of past living organisms. 
Who Discovered It? Nicholas Steno 


Why Is This One of the 100 Greatest? 

The only way we can learn about the ancient past is to examine fossil remains of now 
extinct plants and animals and try to re-create that long-gone life and environment. Scien- 
tists can only do this if they correctly interpret the fossil remains that are dug from ancient 
rock layers. 

That process began with Nicholas Steno. He provided the first true definition of the 
word “fossil” and the first understanding of the origin and nature of fossils. Steno’ s work 
represents the beginning of our modern process of dating and studying fossils and the devel- 
opment of modern geology. 


How Was It Discovered? 

For 2,000 years, anything dug from the earth was called a fossil. By the middle ages, 
fossil had come to be used for only those things made of stone that were dug from the earth 
and that looked remarkably like living creatures. Many thought these fossils were God’s 
practice attempts to create living things. Some claimed they were the Devil’s attempts to 
imitate God. Some believed they were the remains of drowned animals from Noah’s flood. 
No one thought them to be of scientific value. 

Nicholas Steno was born Niels Stensen in 1638 in Copenhagen, Denmark. He changed 
his name to its Latinized form in 1660 when he moved first to Paris and then to Italy to study 
medicine. Steno was a student of Galileo’s experimental and mathematical approach to sci- 
ence and focused his studies on human muscular systems and on using math and geometry 
to show how muscles contracted and moved bones and the skeleton. Steno gained consider- 
able fame in Italy for these anatomical studies. 

In October 1666, two fishermen caught what was described as “a huge shark” near the 
town of Livorno, Italy. Because of its enormous size, Duke Ferdinand ordered that its head 
to be sent to Steno for study. Steno dutifully dissected the head, focusing on the musculature 
of the shark’s deadly jaw. 


25 



26 Fossils 


However, when he examined the shark’ s teeth under a microscope, Steno was struck 
by their resemblance to certain stone fossils called glossopetrae, or “tongue stones,” that 
were found in rock layers throughout the coastal hills. Glossopetrae had been found and 
known since the early Roman Empire. The famed Roman author Pliny the Elder thought 
they were part of the moon that fell from the sky. As Steno compared his monstrous shark 
teeth with glossopetrae samples, he suspected that glossopetrae not only resembled sharks’ 
teeth, they were sharks’ teeth. 

Italian scientists scoffed that glossopetrae couldn’t be from a sea creature because they 
were often found miles from the sea. Steno argued that they must have been deposited in 
shallow water or mud when the ancient shark died and that these areas had somehow been 
lifted up to become dry land. Others countered that glossopetrae couldn’t be teeth since 
sharks’ teeth were not made of stone. 

Steno expanded his study to include fossils that resembled bones and bone fragments. 
When he viewed these under the microscope he was convinced that they, too, had originally 
been bones, not stones. After months of study, Steno used the then new “corpuscular theory 
of matter” (a forerunner of atomic theory) to argue that time and chemical action could alter 
the composition of teeth and bones into stone. 

Steno published his discovery and supporting evidence in 1669. In addition to proving 
that fossils were really the ancient bones of living creatures, Steno investigated how these 
bones came to lie in the middle of rock layers. Through this work he discovered the process 
of sedimentation and of creating sedimentary rock layers. For this discovery Steno is also 
credited with founding modern geology. 

At the height of his scientific career, Steno was ordained a Catholic priest and com- 
pletely abandoned science because he said that science was incompatible with the teachings 
of the Church. Luckily, his discoveries remained to advance and benefit science. 


Archer, Michael. Fossil Hunters: The Job of Paleontologists. New York: Scholastic, 
1999. 

Lutz, Frank. Nicholas Steno. New York: Dover, 1995. 

Mayor, Adrienne. The First Fossil Hunters. Princeton, NJ: Princeton University Press, 


Sternberg, Charles. The Life of a Fossil Hunter. Bloomington: Indiana University 
Press, 1999. 



Fun Facts: When we think of fossils, we think of giant dinosaurs. But, 
the world’s largest rodent fossil remains were discovered in northern 
South America in 2003. The fossil remains of this giant rodent weighed 
1 ,500 pounds (700 kilograms) and dated back some eight million years. 


More to Explore 


2001 . 


Distance to the Sun 

Year of Discovery: 1672 


What Is It? The first accurate calculation of the distance from the earth to the 
sun, of the size of the solar system, and even of the size of the universe. 

Who Discovered It? Giovanni Cassini 


Why Is This One of the 100 Greatest? 

Our understanding of the universe depends on two foundations — our ability to mea- 
sure the distances to faraway stars, and our ability to measure the chemical composition of 
stars. The discovery that allowed scientists to determine the composition of stars is de- 
scribed in the 1859 entry on spectrographs. The distance to the sun has always been re- 
garded as the most important and fundamental of all galactic measurements. Cassini’s 1672 
measurement, however, was the first to accurately estimate that distance. 

Cassini’s discovery also provided the first shocking hint of the truly immense size of 
the universe and of how small and insignificant Earth is. Before Cassini, most scientists be- 
lieved that stars were only a few million miles away. After Cassini, scientists realized that 
even the closest stars were billions (if not trillions) of miles away ! 


How Was It Discovered? 

Born in 1625, Giovanni Cassini was raised and educated in Italy. As a young man he 
was fascinated by astrology, not astronomy, and gained widespread fame for his astrologi- 
cal knowledge. Hundreds sought his astrological advice even though he wrote papers in 
which he proved that there was no truth to astrological predictions. 

In 1668, after conducting a series of astronomical studies in Italy that were widely 
praised, Cassini was offered a position as the director of the Paris Observatory. He soon de- 
cided to become a French citizen and changed his name to Jean Dominique Cassini. 

With an improved, high-powered telescope that he carefully shipped from Italy, 
Cassini continued a string of astronomical discoveries that made him one of the world’s 
most famous scientists. These discoveries included the rotational periods of Mars and Sat- 
urn, and the major gaps in the rings of Saturn — still called the Cassini gaps. 

Cassini was also the first to suspect that light traveled at a finite speed. Cassini refused 
to publish his evidence, and later even spent many years trying to disprove his own theory. 
He was a deeply religious man and believed that light was of God. Light therefore had to be 
perfect and infinite, and not limited by a finite speed of travel. Still, all of his astronomical 
work supported his discovery that light traveled at a fixed and finite speed. 

27 



28 Distance to the Sun 


Because of his deep faith in the Catholic Church, Cassini also believed in an 
Earth-centered universe. By 1672, however, he had become at least partially convinced by 
the early writing of Kepler and by Copernicus’s careful arguments to consider the possibil- 
ity that the sun lay at the center. 

This notion made Cassini decide to try to calculate the distance from the earth to the 
sun. However, it was difficult and dangerous to make direct measurements of the sun (one 
could go blind). Luckily, Kepler’s equations allowed Cassini to calculate the distance from 
the earth to the sun if he could measure the distance from the earth to any planet. 

Mars was close to Earth and well-known to Cassini. So he decided to use his improved 
telescopes to measure the distance to Mars. Of course he couldn’t actually measure that dis- 
tance. But if he measured the angle to a spot on Mars at the same time from two different 
points on Earth, then he could use these angles and the geometry of triangles to calculate the 
distance to Mars. 

To make the calculation work, he would need to make that baseline distance between 
his two points on Earth both large and precisely known. He sent French astronomer Jean 
Richer to Cayenne in French Guiana off the north cost of South America. Cassini stayed in 
Paris. 

On the same August night in 1672, at exactly the same moment, both men measured 
the angle to Mars and placed it exactly against the background of distant stars. When Richer 
returned to Paris with his readings, Cassini was able to calculate the distance to Mars. He 
then used Kepler’s equations to discover that the distance to the sun had to be 87 million 
miles (149.6 million km). Modem science has found that Cassini’s calculation was only 7 
percent off the true distance (just over 93 million miles). 

Cassini went on to calculate the distances to other planets and found that Saturn lay a 
staggering 1,600,000,000 (1.6 billion) miles away! Cassini’s discoveries of distance meant 
that the universe was millions of times bigger than anyone had dreamed. 

tf~^\ Fun Facts: The sun’s diameter is 1.4 million km (875,000 miles). It is 
\k/ approximately 109 times wider than the earth. 

More to Explore 

Brush, Stephen. The History of Modern Astronomy. New York: Garland, 1997. 

Core, Thomas. The Distance from the Sun to the Earth. New York: Dover, 2002. 

Hinks, Arthur. New Measurements of the Distance to the Sun. London: Taylor and 
Francis, 1995. 

Sellers, David. The Transit of Venus: The Quest to Find the True Distance to the Sun. 
New York: Magavelda Press, 2001. 


Year of Discovery: 1680 


Bacteria 


What Is It? Microscopic organisms exist that cannot be seen by the human 
eye. 

Who Discovered It? Anton van Leeuwenhoek 


Why Is This One of the 100 Greatest? 

Just as Galileo used his telescope to open the human horizon to the planets and stars of 
space, so van Leeuwenhoek used his microscope to open human awareness to the micro- 
scopic world that was invisibly small and that no one had even dreamed existed. He discov- 
ered protozoa, bacteria, blood cells, sperm, and capillaries. His work founded the science of 
microbiology and opened tissue studies and plant studies to the microscopic world. He 
completed human understanding of the circulatory system. 


How Was It Discovered? 

Anton van Leeuwenhoek was bom in 1632 in Delft, Holland. With no advanced 
schooling, he was apprenticed as a cloth merchant and assumed that buying and selling 
cloth would be his career. 

But van Leeuwenhoek was curious about the world and interested in mathematics. 
Completely self-taught, he learned enough math to moonlight as a surveyor and read what 
he could about the natural world around him. He never learned any language other than 
Dutch, so he was never able to read any of the scientific papers and research (all written in 
Latin or French). 

Microscopes existed in Holland by 1620. Christian Huygens and Robert Hooke were 
the first two scientists to make scientific use of microscopes. Both designed and built 
two-lens microscopes (two ground glass lenses inside a thin metal barrel). 

In 1657 van Leeuwenhoek looked through his first microscope and was fascinated. He 
tried a two-lens microscope, but was disappointed by its distortion and low resolution. 
When he built his first microscope, he used a highly curved single lens to gain greater 
magnification. 

By 1673 van Leeuwenhoek had built a 270-power microscope that was able to see ob- 
jects only one-one-millionth of a meter in length. Van Leeuwenhoek remained very secre- 
tive about his work and never allowed others to see his microscopes or setup. 


29 



30 Bacteria 


Van Leeuwenhoek started his microscopic studies with objects he could mount on the 
point of a pin — a bee’s mouth parts, fleas, human hairs, etc. He described and drew what he 
saw in precise detail. By 1674 he had developed the ability to focus on a flat dish and turned 
his attention to liquids — water drops, blood cells, etc. 

Those 1674 studies were where he made his great discovery. He discovered a host of 
microscopic protozoa (bacteria) in every water drop. He had discovered microscopic life, 
invisible to the human eye. 

Van Leeuwenhoek expanded his search for these unseeably small creatures and found 
them everywhere: on human eyelashes, on fleas, in dust, and on skin. He drew and de- 
scribed these tiny creatures with excellent, precise drawings. 

Each drawing often took days to complete. As an amateur, Van Leeuwenhoek had to 
work at his science in the evenings and early morning hours when not at work. Embarrassed 
by his lack of language skills and by his poor spelling (even in Dutch), van Leeuwenhoek 
felt hesitant to publish any articles about his wondrous findings. 

Beginning in 1676, he agreed to send letters and drawings to the Royal Society of Lon- 
don. They had them translated into English. That extensive collection of letters (written and 
collected over many decades) formed the first and best map of the microscopic world. What 
van Leeuwenhoek observed shattered many scientific beliefs of the day and put him 
decades — if not centuries — ahead of other researchers. 

He was the first to claim that bacteria cause infection and disease. (No one else be- 
lieved it until Pasteur proved it in 1 856.) Van Leeuwenhoek saw that vinegar killed bacteria 
and said that it would clean wounds. Again, it was two centuries before his belief became 
standard medical practice. 

It was also 200 years before anyone built a better microscope. But with his marvelous 
microscope, van Leeuwenhoek discovered the critically important microscopic world. 

f Fun Facts: In 1999 scientists discovered the largest bacterium ever. The 
organism can grow to as large as .75 mm across — about the size of the 
period at the end of this sentence. The newfound bacterium is 100 times 
larger than the previous record holder. For comparison, if the newly dis- 
covered bacterium was the size of a blue whale, the average bacterium 
would be the size of a newborn mouse. 

More to Explore 

Dobell, Clifford. Anthony van Leeuwenhoek and His “Little Animals. ” New York: 
Dover, 1990. 

Ralston, Alma. The Cleere Observer: A Biography of Antony van Leeuwenhoek. New 
York: Macmillan, 1996. 

Ruestow, E. The Microscope in the Dutch Republic: The Shaping of Discovery. New 
York: Cambridge University Press, 1996. 

Schierbeek, A. Measuring the Invisible World: The Life and Works of Anthony van 
Leeuwenhoek. London: Abelard-Schuman, 1999. 

Yount, Lisa. Antony van Leeuwenhoek: First to See Microscopic Life. Beecher, IL: 
Sagebrush, 2001. 


Laws ol Motion 

Year of Discovery: 1687 


What Is It? The fundamental relationships of matter, force, and motion upon 
which are built all physical science and engineering. 

Who Discovered It? Isaac Newton 


Why Is This One of the 100 Greatest? 

Newton’s three laws of motion form the very the foundation of physics and engineer- 
ing. They are the underlying theorems that our physical sciences are built upon, just as Eu- 
clid’s basic theorems form the foundation of our modern geometry. For the creation of these 
laws, combined with his discovery of gravity and his creation of calculus, Newton is con- 
sidered the preeminent scientific intellect of the last millennium. 


How Was It Discovered? 

Ever since Johannes Kepler’s 1609 discovery that planets travel in elliptical (not circu- 
lar) orbits around the sun, scientists had been frantically trying to mathematically explain 
these orbits. Robert Hooke and John Halley both tried. But neither could make the 
mathematics work. 

Born in 1642 in Lincolnshire, England, 60 miles from Cambridge, Isaac Newton was a 
difficult child. His father died three months before Isaac’s birth. Isaac never liked his step- 
father and was left to be raised by his grandparents. But Newton felt no affection toward 
anyone — not his mother, not his grandparents, nor even his half-brother and sister. He often 
threatened to hit them and to burn down the house. He was a discipline problem in school. 

Only one man, William Ayscough, recognized Isaac’s brilliance and potential and ar- 
ranged for Newton to study at Trinity College (part of Cambridge University). Being poor 
and unable to pay the large tuition, Newton worked as a servant to other students to pay for 
room and board. Newton was always solitary and secretive. Others said he was surly and 
argumentative. 

In 1665 Cambridge closed when the plague struck London. Newton retired to his sis- 
ter’s country estate. There he felt frustrated by the isolation and by a lack of mathematical 
tools to describe the changing forces and motions he wanted to understand. He was deter- 
mined to master the forces that made things move (or not move). 

Newton studied writings by Galileo and Aristotle as well as the more recent works by 
Kepler and Halley. He gathered the scattered and often contradictory observations and the- 
ories developed since the time of the early Greeks. He studied and refined them, searching 

31 



32 Laws of Motion 


for common truths and for errors. Newton was amazingly good at sifting through this moun- 
tain of ideas for the few that held truth. 

Newton was not much of an experimenter. He thought about problems, conducting 
mind experiments as did Einstein. Newton thought about things intently for a long time un- 
til he formed the answers he needed. In his own words, he “kept the subject constantly be- 
fore him and waited until the first dawnings opened little by little into full light.” 

Solving the mystery of the forces that create motion quickly became an obsession with 
Newton. He focused his attention on Galileo’s laws of falling bodies and on Kepler’s laws 
about the motion of planets. He often went without sleep or food, to the edge of physical 
breakdown. 

Newton developed his three laws of motion in early 1666. They were the essential 
building blocks for his creation of calculus and his discovery of gravity. However, Newton 
did not publish these laws until Halley coaxed him to write Principia 20 years later. 

In 1684 Jean Picard produced the first accurate figures for the size and mass of Earth. 
This finally gave Newton the numbers he needed to prove that his laws of motion combined 
with his equation for gravity correctly predicted the actual orbits of the planets. Even after 
completing this mathematical proof, Newton only published Principia in 1687 because 
Halley begged and cajoled him to — mostly because Robert Hooke claimed (falsely) to have 
developed universal laws of motion himself. Principia became one of the most revered and 
most used publications in the history of science. 


Boorstin, Daniel. The Discoverers: A History of Man ’s Search to Know His World and 
Himself. New York: Random House, 1997. 

Christianson, Gale. Isaac Newton and the Scientific Revolution. New York: Oxford 
University Press, 1996. 

Gale, Christeanson. In the Presence of the Creator: Isaac Newton and His Times. New 
York: Collier Macmillan, 1994. 

Gleick, James. Isaac Newton. New York: Vintage, 2004. 

Maury, Jean. Newton: The Father of Modern Astronomy. New York: Harry Abrams, 
1996. 

Peteson, Ivars. Newton ’s Clock. New York: W. H. Freeman, 1995. 

Westfall, Richard. The Life of Isaac Newton. New York: Cambridge University Press, 



Fun Facts: For every motion, there is a force. Gary Hardwick of 
Carlsbad, California, created enough force to set a skateboard speed re- 
cord (standing position) of 100.66 km/h (62.55 mph) at Fountain Hills, 
Arizona, on September 26, 1998. 


More to Explore 


1997. 


White, Michael. Isaac Newton: The Last Sorcerer. Jackson, TN: Perseus Books, 1999. 


Order in Nature 


Year of Discovery: 1735 


What Is It? All living plants and animals can be grouped and organized into a 
simple hierarchy. 

Who Discovered It? Carl Linnaeus 


Why Is This One of the 100 Greatest? 

Until the eighteenth century, nature was viewed as a wild profusion of life. Carl Linnaeus 
discovered order and organization in that seeming randomness. His system for naming, group- 
ing, and conceptually organizing plants and animals provided insights into botany, biology, 
ecosystems, and biological structure that scientists still rely on almost 300 years later. 

For his discovery, Carl Linnaeus is called the father of modem taxonomy. (“Taxonomy” is 
Greek for “naming in order.”) The proof of his influence over, and importance to, modem sci- 
ence can be seen in two ways. First, all of science still uses his system and still uses Latin names 
for existing and new species as Linnaeus did — the last vestige of that ancient language once the 
universal language of science. Every newly discovered species is immediately classified and 
named according to Linnaeus’s system. Second, every biologist has used Linnaeus’s system to 
organize, understand, identify, and refer to every plant and animal species. 

Linnaeus was the first to identify humans as homo sapiens and place humans in the 
greater flow of life as part of the primate order. His classification system was the origin of 
the concept of a “tree of life” since every living thing belonged to a species, genus, family, 
class, order, and phyla and to the plant or animal kingdom — analogous to the twigs, 
branches, and trunk of a tree. 

How Was It Discovered? 

Carl Linnaeus hated disorder. He claimed he could never understand anything that was 
not systematically ordered. Born in Sweden in 1707, he was supposed to become a priest 
like his father. But Carl showed little aptitude for, and no interest in, the priesthood and was 
finally allowed to switch to medicine. 

He entered the University of Lund’s School of Medicine in 1727 but spent more time 
in the university’s small botanical garden than in class. Linnaeus had been fascinated by 
plants and flowers since he was a small child. In 1728 Linnaeus transferred to the University 
of Uppsala (partly because they had bigger botanical gardens). There he read a paper by 
French botanist Sebastian Vaillant that claimed (it was considered shockingly revolution- 


33 



34 Order in Nature 


ary at the time) that plants reproduced sexually and had male and female parts that corre- 
sponded to the sexual organs of animals. 

The idea appealed to Linnaeus. As an obsessive cataloger, he had always detested the 
notion that each of the thousands of plants he saw in botanical gardens were individual and 
separate species. Linnaeus began to wonder if he could use the differences in plants’ repro- 
ductive parts as a means of classifying and ordering the vast array and profusion of plants. 
His dream of bringing order to the chaos of nature was bom. 

Glib, cordial, and with a natural talent for ingratiating himself with rich and powerful sup- 
porters, Linnaeus was able to arrange financial support for a series of expeditions across different 
areas of Sweden to study and catalog plant species. He spent months tramping across the country- 
side listing, describing, and studying every plant he found. His expeditions were always the pic- 
ture of perfect order. He started each day ’ s hike precisely at 7 :00 in the morning. Linnaeus stopped 
for a meal break at 2:00 P.M. He paused for a rest and lecture break at 4:00 P.M. 

During these expeditions, Linnaeus focused his studies on the reproductive systems of 
each plant he found. Soon he discovered common characteristics of male and female plant 
parts in many species that he could group into a single category. He lumped these categories 
together into larger groups that were, again, combined with other groups into yet larger 
classifications. He found that plants fit neatly into groups based on a few key traits and that 
order did exist in the natural world. 

By 1735 he had described more than 4,000 species of plants and published his classifi- 
cation system in a book, Systema Naturae. This system described the eight levels Linnaeus 
finally built into his system: species, genus, family, order, Class, Subphylum, Phylum, and 
Kingdom. This system — based solely on the sexual elements of plants and (later) animals — 
was controversial with the public. But botanists found it easy to use and appealing. 

Linnaeus’s system spread quickly across Europe and was often drawn as a tree, with 
giant branches being classes, down to the tiniest twigs of species. From these drawings 
came the concept of a “Tree of Life.” 

Linnaeus spent the next 30 years touring Europe adding new plants to his system. In 
1740 he added animal species into his system. By 1758 he had described and classified 
4,400 animal species and more than 7,700 plant species. 

In 1758, with the tenth edition of his book, he introduced the binomial (two-name) sys- 
tem of naming each plant and animal by species and genus. With that addition, Linnaeus’s 
system was complete. He had discovered both that order existed in the natural world and a 
system for describing that order — a system still very much alive and in use today. 

| Fun Facts: The world’s most massive living tree is General Sherman, 
vjj/ 1 the giant sequoia (Sequoiadendron giganteum) growing in the Sequoia 
® National Park in California. It stands 83.82m (274.9 ft.) tall and has a di- 
ameter of 11.1 m (36 ft., 5 in.). This one tree is estimated to contain 
enough wood to make five billion matches — one for almost every person 
on Earth. 


More to Explore 35 


More to Explore 

Anderson, Margaret. Carl Linnaeus: Father of Classification. Berkeley Heights, NJ: 
Enslow, 2001. 

Dickenson, Alice. Carl Linnaeus. New York: Franklin Watts, 1995. 

Fara, Patricia. Sex, Botany, and Empire: The Story of Carl Linnaeus and Joseph 
Banks. New York: Columbia University Press, 2004. 

Hagberg, Knut. Carl Linnaeus. New York: Dutton, 1992. 

Stoutenburg, Adrien. Beloved Botanist: The Story of Carl Linnaeus. New York: 
Scribner, 1994. 

Tore, Frangsmyr, ed. Linnaeus: The Man and His Work. Berkeley: University of Cali- 
fornia Press, 2001. 


Galaxies 


Year of Discovery: 1750 


What Is It? Our sun is not the center of the universe but is rather part of a giant, 
disc-shaped cluster of stars that floats through space. 

Who Discovered It? Thomas Wright and William Herschel 


Why Is This One of the 100 Greatest? 

The discovery that stars are clumped into galaxies represents the first advance in ef- 
forts to describe the actual shape of the universe and the distribution of stars in it. Wright's 
theory of galaxies was the first astronomical work to place our sun not in the center of the 
universe, but in a tightly packed cluster of stars that Wright called a galaxy. This discovery 
led science a giant step forward in its efforts to understand the vast universe of which our 
sun and Earth represent only tiny and very ordinary specks. Twenty-five years later, 
Herschel conducted careful observational studies that proved Wright was right. 


How Was It Discovered? 

For thousands of years scientist believed that the universe consisted of a vast spherical 
shell of stars, with Earth at its center. Nothing existed in the immense void between Earth 
and that shell of stars except the few planets and the sun. 

By the mid- 1600s, most scientists acknowledged that the sun, not the earth, sat at the 
center of the spherical universe. Some prominent scientists (Christian Huygens, for exam- 
ple) believed that stars were really holes in the black sphere of space where light from a lu- 
minous region of perpetual day beyond shined through. 

Two men’s discoveries combined to establish the existence of dense clusters of stars 
called galaxies. Born in 171 1, Englishman Thomas Wright taught mathematics and naviga- 
tion but was a passionate amateur astronomer. As had many astronomers before him, 
Wright observed that the stars were not evenly spread across the sky. A seeming cloud of 
faint stars was densely packed along the band called the Milky Way. 

This bothered Wright. He believed that God had created a universe of perfect order. 
That should mean that stars were neatly and evenly — perfectly — spaced across the heavens. 
Wright could not accept that the heavens were not perfect and so began to play with 
schemes for the placement of stars to make them really be uniform in their placement even 
though they appeared not to be. 


36 



More to Explore 37 


Wright considered that the stars might be spread along the surfaces of a field of giant 
bubbles. If we were packed along one of those rings of stars, looking along the ring would 
cause us to see more stars than if we looked straight out from it. He then considered the rings 
of Saturn and proposed that the stars might be packed into wide rings or a thin disk. If we 
were in that disc, it would account for the uneven distribution of stars we saw — even if the 
stars were really evenly spaced across that disk. 

In 1750 Wright published a book, An Original Theory on New Hypothesis of the Uni- 
verse, in which he proposed this theory. He was the first to use the word galaxy to describe a 
giant cluster of stars. Five years later, famed astronomer and mathematician Immanuel Kant 
proposed a similar arrangement of the stars into a giant disk-shaped cluster. 

English astronomer William Hershel (bom in 1738) read with interest Wright’s theory. 
In 1785 Herschel decided to use statistical methods to count the stars. He surely couldn’t count 
them all. So he randomly picked 683 small regions of the sky and set about counting the 
stars in each region using a 48-inch telescope — considered a giant scope at the time. 
Herschel quickly realized that the number of stars per unit area of sky rose steadily as he ap- 
proached the Milky Way and spiked in regions in the Milky Way. (The number of stars per 
unit area of sky reached a minimum in directions at right angles to the Milky Way.) 

This made Herschel think of Wright’s and Kant’s theories. Hershel concluded that his 
counting results could only be explained if most of the stars were compacted into a 
lens-shaped mass and that the sun was buried in this lens. Herschel was the first to add sta- 
tistical measurement to Wright’s discovery of the existence and shape of galaxies. 


Greenstein, George. Portraits of Discovery: Profiles in Scientific Genius. New York: 
John Wiley & Sons, 1997. 

Hubbard, Elbert. William Hershel. Whitefish, MT: Kessinger, 2001. 

Roan, Carl. The Discovery of the Galaxies. San Francisco: Jackdaw Publications, 


Taschek, Karen. Death Stars, Weird Galaxies, and a Quasar-Spangled Universe. Al- 
buquerque: University of New Mexico Press, 2006. 

Whitney, Charles Allen. Discovery of Our Galaxy. Iowa City: Iowa State Press, 1997. 



V Fun Facts: The central galaxy of the Abell 2029 galaxy cluster, 1,070 
J million light years distant in Virgo, has a diameter of 5,600,000 light 
' years, 80 times the diameter of our own Milky Way galaxy. 


More to Explore 


2000 . 


The Nature of Electricity 

Year of Discovery: 1752 


What Is It? All forms of electricity are the same. 
Who Discovered It? Benjamin Fran kl in 


Why Is This One of the 100 Greatest? 

Electricity is one of our greatest energy resources and one of the few natural energy 
sources. Franklin’s electricity experiments were the first scientific ventures into the nature 
and use of electricity and uncovered its true nature. They set the stage for much of the scien- 
tific and engineering development in the nineteenth century and for the explosion of electri- 
cal development — batteries, motors, generators, lights, etc. 


How Was It Discovered? 

All that was known about electricity in the mid-eighteenth century was that there were 
two kinds of it: playful static and deadly lightning. Benjamin Franklin was the first scientist 
to begin serious electrical experiments (in 1746). He was also the first to suspect that static 
and lightning were two forms of the same thing. 

Franklin had been experimenting with Feyden jars — large glass jars, partially filled 
with water and wrapped with tin foil both inside and out. A rod extended through an insulat- 
ing cork out the top of the jar to a metal knob. Once a Feyden jar was charged with a hand 
crank, anyone who grabbed the knob got a resounding shock. 

Franklin found ways to more than double the amount of electricity his Feyden jars car- 
ried, and he invented a way to connect them in series so that they could, collectively, carry 
an almost deadly punch. 

During a 1752 demonstration for friends, Franklin accidentally touched a Feyden jar’s 
knob. With a sharp crack, a sizzling blue arc leapt from jar to Franklin’s hand. He shot back 
half a dozen feet and crashed to the floor. Franklin realized that that jolt looked exactly like 
a mini-lightning bolt. 

He decided to prove that static and lightning were the same by designing a Feyden 
jar-like electric circuit to let electricity flow from clouds just as it did into ajar. 

Franklin’s “circuit” was made of a thin metal wire fixed to a kite (to gather electricity 
from the clouds) and tied to a twine kite string. Electricity would flow down the twine to a 
large iron key tied to the bottom. Franklin tied the other end of the key to a nonconducting 
silk ribbon that he would hold. Thus, electricity would be trapped in the key, just as it was in 
a Feyden jar. 


38 



More to Explore 39 


When an afternoon storm brewed up dark and threatening a few weeks later, Franklin 
rushed to launch his kite. The wind howled and the clouds boiled. A cold rain pounded 
down about Franklin’s upturned collar. The kite twisted and tore at the air like a rampaging 
bull. 

Then it happened. No, a lightning bolt did not strike the kite, as has often been re- 
ported. And a good thing, too. A French scientist was killed a few months later by a light- 
ning strike when he tried to repeat Franklin’s experiment. No, what happened that stormy 
afternoon was that the twine began to glow a faint blue. The twine’s fibers lifted and bristled 
straight out. Franklin could almost see electricity trickling down the twine as if electricity 
were liquid. 

Franklin reached out a cautious hand closer and closer to the key. And pop! A spark 
leapt to his knuckle and shocked him — just l ik e a Leyden jar. 

Lightning and static were all the same, fluid electricity ! 

The practical outcome of this experiment was Franklin’s invention of the lightning 
rod, credited with saving thousands of houses and lives over the next 100 years. More im- 
portant, Franklin’s work inspired experiments by Volta, Faraday, Oersted, and others in 
early part of the nineteenth century that further unraveled electricity’s nature. 


Brands, H. W. Benjamin Franklin: The Original American. New York: Barnes & 
Noble, 2004. 

Fradin, Dennis. Who Was Benjamin Franklin? New York: Penguin Young Readers’ 
Group, 2002. 

Isaacson, Walter. Benjamin Franklin: An American Life. New York: Simon & 
Schuster, 2003. 

McCormick, Ben. Ben Franklin: America’s Original Entrepreneur. New York: 
McGraw-Hill, 2005. 

Morgan, Edmund. Benjamin Franklin. New Haven, CT: Yale University Press, 2003. 

Sandak, Cass. Benjamin Franklin. New York: Franklin Watts, , 1996. 

Skousen, Mark, ed. Completed Autobiography of Benjamin Franklin. Washington, 
DC: Regnery Publishing, 2005. 

Wright, Esmond. Franklin of Philadelphia. Cambridge, MA: Harvard University 
Press, 1996. 



V Fun Facts: Popeye uses spinach to power his muscles. Now scientists 
/ are looking to spinach as a power source for supplying electricity. Chern- 
' ical substances extracted from spinach are among the ingredients needed 
to make a solar cell that converts light into electricity. 


More to Explore 


Oceans Control Global 
Weather 


Year of Discovery: 1770 


What Is It? By pumping massive amounts of heat through the oceans, vast 
ocean currents control weather and climate on land. 

Who Discovered It? Benjamin Franklin 


Why Is This One of the 100 Greatest? 

The Atlantic Ocean’s Gulf Stream is the most important of our world’s ocean currents. 
It is a major heat engine, carrying massive amounts of warm water north to warm Europe. It 
has directed the patterns of ocean exploration and commerce and may be a major determi- 
nant of the onset of ice ages. Finally, it is the key to understanding global circulation pat- 
terns and the interconnectedness of the world’s oceans, weather, and climates. 

American statesman, inventor, and scientist Benjamin Franklin conducted the first sci- 
entific investigation of the Gulf Stream and discovered its importance to Earth’s weather 
and climate. His work launched scientific study of ocean currents, ocean temperature, the 
interaction of ocean current with winds, and the effect of ocean currents on climate. Frank- 
lin’s discoveries mark the beginnings of modern oceanographic science. 


How Was It Discovered? 

Benjamin Franklin set out to map the Gulf Stream in order to speed transatlantic ship- 
ping. He wound up discovering that ocean currents are a major controlling factor of global 
climate and weather. 

Ocean surface currents were noted by early Norse sailors as soon as they sailed the 
open Atlantic. Columbus and Ponce de Feon described the Gulf Stream current along the 
coast of Florida and in the strait between Florida and Cuba. Others noted North Atlantic cur- 
rents over the next hundred years. However, no one charted these currents, recorded them 
on maps, or connected the individual sightings into a grand, oceanwide system of massive 
currents. 

In 1769 British officials in Boston wrote to Fondon complaining that the British pack- 
ets (small navy ships that brought passengers and mail to the colonies) took two weeks lon- 
ger in their trans- Atlantic crossing than did American merchant ships. Benjamin Franklin, 
an American representative in Fondon at the time, heard this report and refused to believe it. 

40 



How Was It Discovered? 41 


Packet ships rode higher in the water, were faster ships, and were better crewed than heavy 
Rhode Island merchant ships. 

Franklin mentioned the report to a Rhode Island merchant captain off-loading cargo in 
London. This captain said it was absolutely true and happened because Rhode Island whal- 
ers had taught American merchant captains about the Gulf Stream, a 3 mph current that 
spread eastward from New York and New England toward England. American captains 
knew to curve either north or south on westward trips to avoid fighting this powerful 
current. 

When Franklin checked, the Gulf Stream didn’t appear on any maps, nor did it appear 
in any of the British Navy shipping manuals. Franklin began interviewing merchant and 
whaling captains, recording on maps and charts their experience with the Gulf Stream cur- 
rent. Whalers, especially, knew the current well because whales tended to congregate along 
its edges. 

By 1770 Franklin had prepared detailed maps and descriptions of this current. British 
Navy and merchant captains, however, didn’t believe him and refused to review his infor- 
mation. By 1773 rising tensions between England and the colonies made Franklin withhold 
his new findings from the British. 

Franklin began taking regular water temperature readings on every Atlantic Ocean 
crossing. By 1783 he had made eight crossings, carefully plotting the exact course his ship 
took each time and marking his temperature readings on the ship’s map. 

On his last voyage from France to America, Franklin talked the ship’s captain into 
tracking the edge of the Gulf Stream current. This slowed the voyage as the ship zigzagged 
back and forth using the warm water temperature inside the Gulf Stream and the colder wa- 
ter temperature outside it to trace the current’s boundary. 

The captain also allowed Franklin to take both surface and subsurface (20 and 40 fath- 
oms) temperature readings. Franklin was the first to consider the depth (and thus the vol- 
ume) of an ocean current. 

Franklin discovered that the Gulf Stream poured masses of warm water (heat) from the 
tropical Caribbean toward northern Europe to warm its climate. He began to study the inter- 
action between wind and current and between ocean currents and weather. Through the 
brief papers he wrote describing the Gulf Stream data he had collected, Franklin brought 
science’s attention and interest to ocean currents and their effect on global climate. 

Franklin’s description of the Gulf Stream was the most detailed available until German 
scientist Alexander von Humbolt published his 1814 book about the Gulf Stream based on 
his measurements from more than 20 crossings. These two sets of studies represent the be- 
ginnings of modern oceanographic study. 


Fun Facts: The Gulf Stream is bigger than the combined flow of the 
Mississippi, the Nile, the Congo, the Amazon, the Volga, the Yangtze, 
and virtually every other major river in the world. 


42 Oceans Control Global Weather 


More to Explore 

Brands, H. W. Benjamin Franklin: The Original American. New York: Barnes & No- 
ble, 2004. 

Fradin, Dennis. Who Was Benjamin Franklin? New York: Penguin Young Readers’ 
Group, 2002. 

Isaacson, Walter. Benjamin Franklin: An American Life. New York: Simon & 
Schuster, 2003. 

McCormick, Ben. Ben Franklin: America’s Original Entrepreneur. New York: 
McGraw-Hill, 2005. 

Morgan, Edmund. Benjamin Franklin. New Haven, CT: Yale University Press, 2003. 

Sandak, Cass. Benjamin Franklin. New York: Franklin Watts, 1996. 

Skousen, Mark, ed. Completed Autobiography of Benjamin Franklin. Washington, 
DC: Regnery Publishing, 2005. 

Wright, Esmond. Franklin of Philadelphia. Cambridge, MA: Harvard University 
Press, 1996. 


Year of Discovery: 1774 


Oxygen 


What Is It? The first gas separated and identified as a unique element. 
Who Discovered It? Joseph Priestley 


Why Is This One of the 100 Greatest? 

Priestley’s discovery of oxygen sparked a chemical revolution. He was the first person 
to isolate a single gaseous element in the mixture of gasses we call “air.” Before Priestley’s 
discovery, scientific study had focused on metals. By discovering that air wasn’t a uniform 
thing, Priestley created a new interest in the study of gasses and air. 

Because oxygen is a central element of combustion, Priestley’s discovery also led to 
an understanding of what it means to burn something and to an understanding of the conver- 
sion of matter into energy during chemical reactions. 

Finally, Priestley established a simple but elegant and effective process for conducting 
analysis of new gasses and gaseous elements. What did it look like? Would it burn (first a 
candle and then wood splinters)? Would it keep a mouse alive? Was it absorbed by water? 


How Was It Discovered? 

Reverend Joseph Priestley was more fascinated by air than by his church duties. Air 
was one of the four traditional elements (with fire, water, and earth). But Priestley felt 
driven to find out what air was made of. 

Other scientists wrote of creating new gasses that bubbled up during chemical reac- 
tions. Some had described these as “wild gasses” that built up enough pressure to explode 
glass jars or to triple the rate at which wood burned. But none had successfully isolated and 
studied these new gasses. 

Priestley’s imagination soared. He felt compelled to seek out and study these wild, un- 
tamed gasses. 

In early 1774 Priestley decided the only way to isolate and study these new gasses was 
to trap them under water in an upside down (inverted), water-filled glass jar in which there 
was no air. 

He decided to begin by burning solid mercurius calcinatus and studying the gas that 
reaction had been reported to create. 

On August 1, 1774, Priestley used a powerful magnifying lens to focus sunlight on a 
bottle of powdered mercurius calcinatus. A cork stopper sealed this bottle with a glass tube 
leading from it to a washtub full of water, where water-filled glass jars stood inverted on a 

43 



44 Oxygen 


wire mesh stand. Priestley’s glass tube ended just under the open mouth of one of these bot- 
tles so that whatever gas he produced would bubble up into, and be trapped in, that glass jar. 

As his powdered mercury compound heated, clear bubbles began to drift up from the 
end of the glass tube. The jar began to fill. Priestley filled three bottles with the gas and was 
thus the first human to successfully trap this mysterious gas. But what was it? 

Priestley carefully raised one bottle out of the water. He held a lit candle beneath its 
mouth. The dim glow around the candle’s wick erupted into a brilliant ball of fire. As re- 
ported, this strange gas did force substances to burn fiercely. 

Priestley placed a new jar, filled with ordinary air, upside down on the wire stand next 
to a second jar of his mystery gas. He placed a mouse in each jar, and waited. The mouse in 
ordinary air began to struggle for breath in 20 minutes. The mouse in his second jar of this 
strange gas breathed comfortably for over 40 minutes ! 

There seemed only one name for this amazing gas: “pure air.” Priestley carefully 
raised a jar of “pure air” out of his tub. He jammed his own nose into its wide mouth. His 
heart began to beat faster. He closed his eyes, gathered his courage, and breathed in as 
deeply as he could. 

Joseph felt nothing odd from this breath. He tried a second breath and felt happy and 
filled with energy. Priestley’s breath felt particularly light and easy for some time after- 
ward. It took another scientist, Antoine Lavoisier in Paris, to give Priestley’s “pure air” the 
name we know it by today: “oxygen.” 


Bowden, Mary, ed. Joseph Priestley: Radical Thinker. Philadelphia: Chemical Heri- 
tage Foundation, 2005. 

Conley, Kate. Joseph Priestley and the Discovery of Oxygen. Hockessin, DE: Mitchell 
Lane, 2003. 

Crowther, J. G. Scientists of the Industrial Revolution: Joseph Black, James Watt, Jo- 
seph Priestley, and Henry Cavendish. New York: Dufour Editions, 1996. 

Gibbs, Frank. Joseph Priestley. New York: Doubleday, 1997. 

Irwin, Keith. The Romance of Chemistry. New York: Viking Press, 1996. 

Partington, James. A Short Course in Chemistry. New York: Dover, 1999. 

Schofield, Robert. The Enlightenment of Joseph Priestley. University Park: Pennsyl- 
vania State University Press, 1997. 



Y Fun Facts: Without oxygen, biological death begins to occur within 
J three minutes. Free-diving World Champion Pipin Ferreras holds the 
> world record for holding his breath: 8 minutes, 58 seconds. 


More to Explore 


Photosynthesis 


Year of Discovery: 1779 


What Is It? Plants use sunlight to convert carbon dioxide in the air into new 
plant matter. 

Who Discovered It? Jan Ingenhousz 


Why Is This One of the 100 Greatest? 

Photosynthesis is the process that drives plant production all across Earth. It is also the 
process that produces most of the oxygen that exists in our atmosphere for us to breathe. 
Plants and the process of photosynthesis are key elements in the critical (for humans and 
other mammals) planetary oxygen cycle. 

When Jan Ingenhousz discovered the process of photosynthesis, he vastly improved 
our basic understanding of how plants function on this planet and helped science gain a 
better understanding of two important atmospheric gasses: oxygen and carbon dioxide. 
Modern plant engineering and crop sciences owe their foundation to Jan Ingenhousz’s 
discovery. 


How Was It Discovered? 

Jan Ingenhousz was born in Breda in the Netherlands in 1730. He was educated as a 
physician and settled down to start his medical practice back home in Breda. 

In 1774 Joseph Priestley discovered oxygen and experimented with this new, invisible 
gas. In one of these tests, Priestley inserted a lit candle into a jar of pure oxygen and let it 
burn until all oxygen had been consumed and the flame went out. Without allowing any 
new air to enter the jar, Priestley placed mint sprigs floating in a glass of water in the jar to 
see if the mint would die in this “bad” air. But the mint thrived. After two months, Priestley 
placed a mouse in the jar. It also lived — proving that the mint plant had restored oxygen to 
the jar’s air. But this experiment didn’t always work. Priestley admitted that it was a mys- 
tery and then moved on to other studies. 

In 1777, Ingenhousz read about Priestley’s experiments and was fascinated. He could 
focus on nothing else and decided to investigate and explain Priestley’s mystery. 

Over the next two years, Ingenhousz conducted 500 experiments trying to account for 
every variable and every possible contingency. He devised two ways to trap the gas that a 
plant produced. One was to enclose the plant in a sealed chamber. The other was to sub- 
merge the plant. 


45 



46 Photosynthesis 


Ingenhousz used both systems, but found it easier to collect and study the gas collected 
underwater as tiny bubbles. Every time he collected the gas that a plant gave off, he tested it 
to see if it would support a flame (have oxygen) or if it would extinguish a flame (be carbon 
dioxide). 

Ingenhousz was amazed at the beauty and symmetry of what he discovered. Humans 
inhaled oxygen and exhaled carbon dioxide. Plants did just the opposite — sort of. Plants in 
sunlight absorbed human waste carbon dioxide and produced fresh oxygen for us to 
breathe. Plants in deep shade or at night (in the dark), however, did just the opposite. They 
acted like humans, absorbing oxygen and producing carbon dioxide. 

After hundreds of tests, Ingenhousz determined that plants produced far more oxygen 
than they absorbed. Plants immersed in water produced a steady stream of tiny oxygen bub- 
bles when in direct sunlight. Bubble production stopped at night. Plants left for extended 
periods in the dark gave off a gas that extinguished a flame. When he placed the same plant 
in direct sunlight, it produced a gas that turned a glowing ember into a burning inferno. The 
plant again produced oxygen. 

Ingenhousz showed that this gas production depended on sunlight. He continued his 
experiments and showed that plants did not produce new mass (leaf, stem, or twig) by ab- 
sorbing matter from the ground (as others believed). The ground did not lose mass as a plant 
grew. Ingenhousz showed that new plant growth must come from sunlight. Plants captured 
carbon from carbon dioxide in the air and converted it into new plant matter in the presence 
of sunlight. 

Ingenhousz had discovered the process of photosynthesis. He proved that plants cre- 
ated new mass “from the air” by fixing carbon with sunlight. In 1779 he published his re- 
sults in Experiments Upon Vegetables. The name photosynthesis was created some years 
later and comes from the Greek words meaning “to be put together by light.” 


Allen, J. F., et al., eds. Discoveries in Photosynthesis. New York: Springer- Verlag, 


Asimov, Isaac. How Did We Find Out About Photosynthesis ? New York: Walker & 
Co., 1993. 

Forti, G. Photosynthesis Two Centuries After Its Discovery. New York: 
Springer-Verlag, 1999. 

Ingenhousz, Jan. Jan Ingenhousz: Plant Physiologist. Fondon: Chronica Botanica, 



T; Fun Facts: Some species of bamboo have been found to grow at up to 91 
J cm (3 ft.) per day. You can almost watch them grow! 


More to Explore 


2006. 


1989. 


Conservation of Matter 


Year of Discovery: 1789 


What Is It? The total amount of matter (mass) always remains the same no 
matter what physical or chemical changes take place. 

Who Discovered It? Antoine Lavoisier 


Why Is This One of the 100 Greatest? 

Lavoisier was the first chemist to believe in measurement during and after experi- 
ments. All chemists before had focused on observation and description of the reactions dur- 
ing an experiment. By carefully measuring the weight of each substance, Lavoisier 
discovered that matter is neither created nor destroyed during a chemical reaction. It may 
change from one form to another, but it can always be found, or accounted for. Scientists 
still use this principle every day and call it “conservation of matter.” 

Lavoisier’s work also established the foundation and methods of modem chemistry. 
He did much work with gasses, gave oxygen its name (Joseph Priestley discovered oxygen 
but called it “pure air”) , and discovered that oxygen makes up 20 percent of the atmo- 
sphere. Lavoisier is considered the father of modem chemistry. 


How Was It Discovered? 

In the spring of 1781, Frenchman Antoine Lavoisier’s wife, Marie, translated a paper 
by English scientist Robert Boyle into French. The paper described an experiment with tin 
during which Boyle had noted an unexplained weight change when the tin was heated. 
Boyle, l ik e most scientists, was content to assume that the extra weight had been “created” 
during his chemical experiment. 

Lavoisier scoffed at the notion of mysterious creation or loss of mass (weight) during 
reactions. He was convinced that chemists’ traditional experimental approach was inade- 
quate. During experiments chemists carefully observed and described changes in a sub- 
stance. Lavoisier claimed it was far more important to record what could be measured. 
Weight was one property he could always measure. 

Lavoisier decided to repeat Boyle’s experiment, carefully measure weight, and dis- 
cover the source of the added weight. Antoine carried a small sheet of tin to his delicate bal- 
ancing scales and recorded its weight. Next he placed the tin in a heat-resistant glass flask 
and sealed its lid to contain the entire reaction within the flask. 


47 



48 Conservation of Matter 


He weighed the flask (and the tin inside) before heating it over a burner. A thick layer 
of calx (a light gray tarnish) formed on the tin as it heated — as Boyle had described in his 
paper. 

Lavoisier turned off the burner, let the flask cool, and then reweighed it. The flask had 
not changed weight. He pried off the flask’s lid. Air rushed in, as if into a partial vacuum. 
Antoine removed and weighed the calx-covered tin. It had gained two grams of weight (as 
had Boyle’s). 

Lavoisier deduced that the weight had to have come from the air inside the flask and 
that was why new air rushed into the flask when he opened it. The tin gained two grams as it 
mixed with air to form calx. When he opened the lid, two grams of new air rushed in to re- 
place the air that had been absorbed into calx. 

He repeated the experiment with a larger piece of tin. However, still only two grams of 
air were absorbed into calx. He ran the experiment again and measured the volume of air 
that was absorbed into calx — 20 percent of the total air inside the flask. 

He concluded that only 20 percent of air was capable of bonding with tin. He realized 
that this 20 percent of air must be the “pure air” Priestley had discovered in 1774, and 
Lavoisier named it “oxygen.” 

Through further experiments Lavoisier realized that he had proved something far more 
important. Boyle thought weight, or matter, was “created” during experiments. Lavoisier 
had proved that matter was neither created nor lost during a chemical reaction. It always 
came from someplace and went to someplace. Scientists could always find it if they 
measured carefully. 

The all-important concept of conservation of matter had been discovered. However, 
Lavoisier didn’t release this principle until he published his famed chemistry textbook in 1789. 


Donovan, Arthur. Antoine Lavoisier: Science Administration and Revolution. New 
York: Cambridge University Press, 1996. 

Grey, Vivian. The Chemist Who Lost His Head. Coward, McCann & Geoghegan, New 
York, 1982. 

Holmes, Lawrence. Antoine Lavoisier: The Next Crucial Year or the Source of His 
Quantitative Method of Chemistry. Collingdale, PA: Diane Publishing Co., 1998. 

Kjelle, Marylou. Antoine Lavoisier: Father of Chemistry. Hockessin, DE: Mitchell 
Lane, 2004. 

Riedman, Sarah. Antoine Lavoisier: Scientist and Citizen. Scarborough, ON: Nelson, 


Susac, Andrew. The Clock , the Balance, and the Guillotine: The Life of Antoine 
Lavoisier. New York: Doubleday, 1995. 

Yount, Lisa. Antoine Lavoisier: Founder of Modern Chemistry. Berkeley Heights, NJ : 
Enslow, 2001. 



V Fun Facts: The Furnace Constellation (Fornax) was created to honor the 
J famous French chemist Antoine Favoisier, who was guillotined during 
’ the French Revolution in 1794. 


More to Explore 


1995. 


The Nature of Heat 

Year of Discovery: 1790 


What Is It? Heat comes from friction, not from some internal chemical prop- 
erty of each substance. 

Who Discovered It? Count Rumford 


Why Is This One of the 100 Greatest? 

Scientists believed that heat was an invisible, weightless liquid called caloric. Things 
that were hot were stuffed with caloric. Caloric flowed from hot to cold. They also believed 
that fire (combustion) came from another invisible substance called phlogiston, a vital es- 
sence of combustible substances. As a substance burned, it lost phlogiston to air. The fire 
ended when all phlogiston had been lost. 

These erroneous beliefs kept scientists from understanding the nature of heat and of 
oxidation (including combustion), and stalled much of the physical sciences. Benjamin 
Thompson, who called himself Count Rumford, shattered these myths and discovered the 
principle of friction. This discovery opened the door to a true understanding of the nature of 
heat. 


How Was It Discovered? 

In 1790, 37-year-old Count Rumford was serving the King of Bavaria as a military ad- 
visor. As part of his duties he was in charge of the king’s cannon manufacturing. 

Born in Massachusetts as Benjamin Thompson, Rumford had served as a British spy 
during the American Revolutionary War. Then he spied on the British for the Prussians. In 
1790 he fled to Bavaria and changed his name to Count Rumford. 

The cannon manufacturing plant was a deafeningly noisy warehouse. On one side, 
metal wheel rims and mounting brackets were hammered into shape around wooden wheels 
and cannon carriages. Steam rose from hissing vats as glowing metal plates were cooled in 
slimy water. 

On the other side of the warehouse, great cannons were forged. Molten metal poured 
into huge molds — many 12 feet long and over 4 feet across. Spinning drills scraped and 
gouged out the inside of each cannon barrel. 

Drill bits grew dangerously hot. Streams of water kept them from melting. Hissing 
steam billowed out of the cannon barrels toward the ceiling, where it condensed and dripped 
like rain onto the workers below. 


49 



50 The Nature of Heat 


On one visit, Rumford recognized that great quantities of heat flowed into the air and 
water from those cannon barrels. At that time scientists believed that, as a substance grew 
hotter, more caloric squeezed into it. Eventually caloric overflowed and spilled out in all di- 
rections to heat whatever it touched. 

Rumford wondered how so much caloric (heat) could pour out of the metal of one can- 
non barrel — especially since the cannon barrels felt cold when the drilling started. 

Rumford decided to find out how much caloric was in each barrel and where that calo- 
ric was stored. He fashioned a long trough to catch all the water pouring out of a cannon bar- 
rel while it was being drilled so he could measure its increase in temperature. 

He also directed that extra hoses be sprayed on the drilling to prevent the formation of 
steam. Rumford didn’t want any caloric escaping as steam he couldn’t capture and measure. 

Drilling began with a great screeching. Hoses sprayed water onto the drill bits. The 
metal began to glow. A torrent of heated water eight inches deep tumbled down the narrow, 
foot-wide trough and past the Count and his thermometers. 

Rumford was thrilled. More caloric flowed out of that cannon barrel than he could 
have imagined in even his wildest dreams. And still the hot water continued to flow past 
him, all of it heated to more than 50 degrees Celsius. 

Eventually the Count’s face soured. Something was very wrong. The metal cannon 
barrel had already lost more than enough heat (caloric) to turn it into a bubbling pool of liq- 
uid metal many thousands of degrees hot. It seemed impossible for so much caloric to have 
existed in the metal. 

Count Rumford watched the borers go back to work and realized that what he saw was 
motion. As drill bits ground against the cannon’s metal, their motion as they crashed against 
the surface of the metal must create heat. Movement was being converted into heat\ 

Today we call it friction, and know it is one of the primary sources of heat. But in 1790, 
no one believed Count Rumford’ s new theory of friction heat, and they held onto the notion 
of caloric for another 50 years. 

(f~f | Fun Facts: Friction with air molecules is what burns up meteors as they 
\T/ plunge into the atmosphere. That same friction forced NASA to line the 
® bottom of every space shuttle with hundreds of heat-resistant ceramic 
tiles. Failure of one of those tiles led to the explosion of the Columbia in 
2004. 


More to Explore 

Brown, Sanborn. Benjamin Thompson, Count Rumford. Boston: MIT Press, 1996. 

. Collected Works of Count Rumford. Cambridge, MA: Harvard University 

Press, 1994. 

. Count Rumford: Physicist Extraordinary. Westport, CT: Greenwood, 1995. 

Ellis, George. Memoir of Benjamin Thompson, Count Rumford. Somerset, PA: New 
Library Press, 2003. 

van den Berg, J. H. Two Principal Laws of Thermodynamics: A Cultural and Histori- 
cal Exploration. Pittsburgh: Duquesne University Press, 2004. 


Erosion ol the Earth 

Year of Discovery: 1792 


What Is It? The earth’s surface is shaped by giant forces that steadily, slowly 
act to build it up and wear it down. 

Who Discovered It? James Hutton 


Why Is This One of the 100 Greatest? 

In the eighteenth century scientists still believed that Earth’s surface had remained un- 
changed until cataclysmic events (the great flood of Noah’s ark fame was the most often 
sited example) radically and suddenly changed the face of our planet. They tried to under- 
stand the planet’s surface structures by searching for those few explosive events. Attempts 
to study the earth, its history, its landforms, and its age based on this belief led to wildly in- 
accurate guesses and misinformation. 

James Hutton discovered that the earth’s surface continually and slowly changes, 
evolves. He discovered the processes that gradually built up and wore down the earth’s sur- 
face. This discovery provided the key to understanding our planet’s history and launched 
the modern study of earth sciences. 


How Was It Discovered? 

In the 1780s, 57-year-old, more-or-less retired physician and farmer (and amateur geolo- 
gist) James Hutton decided to try to improve on the wild guesses about the age of the earth that 
had been put forth by other scientists. Hutton decided to study the rocks of his native Scotland 
and see if he could glean a better sense of Earth’s age by studying the earth’s rocks. 

Lanky Hutton walked with long pendulum-like strides across steep, rolling green hills. 
Soon he realized that the existing geological theory — called catastrophism — couldn’t possi- 
bly be right. Catastrophism claimed that all of the changes in the earth’s surface were the re- 
sult of sudden, violent (catastrophic) changes. (Great floods carved out valleys in hours. Great 
wrenchings shoved up mountains overnight.) Hutton realized that no catastrophic event could 
explain the rolling hills and meandering river valleys he hiked across and studied. 

It was one thing to say that an existing popular theory was wrong. But it was quite an- 
other to prove that it was wrong or to suggest a replacement theory that better explained 
Earth’s actual surface. Hutton’s search broadened as he struggled to discover what forces 
actually formed the hills, mountains, valleys, and plains of Earth. 

Late that summer Hutton stopped at a small stream tumbling out of a steep canyon. 
Without thinking, he bent down and picked up a handful of tiny pebbles and sand from the 

51 



52 Erosion of the Earth 


streambed. As he sifted these tiny rocks between his fingers, he realized that these pebbles 
had drifted down this small stream, crashing and breaking into smaller pieces as they went. 
They used to sit somewhere up higher on the long ridge before him. 

This stream was carrying dirt and rock from hilltop to valley floor. This stream was re- 
shaping the entire hillside — slowly, grain by grain, day by day. Not catastrophically as ge- 
ologists claimed. 

The earth, Hutton realized, was shaped slowly, not overnight. Rain pounding down on 
hills pulled particles of dirt and rock down into streams and then down to the plains. 
Streams gouged out channels, gullies, and valleys bit by bit, year by year. 

The wind tore at hills in the same way. The forces of nature were everywhere tearing 
down the earth, leveling it out. Nature did this not in a day, but over countless centuries of 
relentless, steady work by wind and water. 

Then he stopped. If that were true, why hadn’t nature already leveled out the earth? 
Why weren’t the hills and mountains worn down? There must be a second force that builds 
up the land, just as the forces of nature tear it down. 

For days James Hutton hiked and pondered. What built up the earth? It finally hit him: 
the heat of Earth’s core built up hills and mountains by pushing outward. 

Mountain ranges were forced up by the heat of the earth. Wind and rain slowly wore 
them back down. With no real beginning and no end, these two great forces struggled in dy- 
namic balance over eons, the real time scale for geologic study. 

With that great discovery, James Hutton forever changed the way geologists would 
look at the earth and its processes, and he completely changed humankind’s sense of the 
scale of time required to bring about these changes. 

Fun Facts: Millions of years ago flowing water eroded the surface of 
Mars, leaving behind the gullies, banks, and dry riverbeds scientists have 
9 found there. Now Mar’s atmosphere is too thin to support liquid water. A 
cup of water on Mars would instantly vaporize and vanish, blown away 
by the solar winds. 

More to Explore 

Baxter, Stephen. Ages in Chaos : James Hutton and the Discovery of Deep Time. New 
York: Forge Books, 2004. 

Geologic Society of London. James Hutton — Present and Future. London: Geologic 
Society of London, 1999. 

Gould, Stephen. Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of 
Geological Time. Cambridge, MA: Harvard University Press, 1997. 

Hutton, James. Theory of the Earth. Whitefish, MT: Kessinger Publishing, 2004. 

McIntyre, Donald. James Hutton: The Founder of Modern Geology. Edinburgh, Scot- 
land: National Museum of Scotland, 2002. 

Repcheck, Jack. The Man Who Found Time: James Hutton and the Discovery of 
Earth’s Antiquity. Jackson, TN: Perseus Books Group, 2003. 


Vaccinations 


Year of Discovery: 1798 


What Is It? Humans can be protected from disease by injecting them with mild 
forms of the very disease they are trying to avoid. 

Who Discovered It? Lady Mary Wortley Montagu and Edward Jenner 


Why Is This One of the 100 Greatest? 

Have you had smallpox? Polio? Typhoid? Probably not. 

However, such infectious diseases used to plague humankind. The word plague comes 
from one of these killer diseases — the bubonic plague. Throughout the fourteenth and fif- 
teenth centuries, the plague killed nearly half of the population of Europe. 

Smallpox killed over 100,000 people a year for a century and left millions horribly 
scarred and disfigured. The influenza epidemic of 1918 killed 25 million worldwide. Polio 
killed thousands in the early twentieth century and left millions paralyzed. 

One simple discovery not only stopped the spread of each of these diseases, it virtually 
eradicated them. That discovery was vaccinations. Vaccinations have saved millions of 
lives and have prevented unimaginable amounts of misery and suffering. American chil- 
dren are now regularly vaccinated for as many as 15 diseases. 


How Were Vaccinations Discovered? 

Twenty-four-year-old Lady Mary Wortley Montagu, a well-known English poet, trav- 
eled to Turkey with her husband in 1712 when he became the British ambassador. Lady 
Mary noticed that native populations in Turkey didn’t suffered from smallpox, the dread 
disease that had left her scarred and pockmarked and that killed tens of thousands in 
England each year. 

She soon learned that elderly tribal women performed what was called “ingrafting.” 
Previous British travelers had dismissed the practice as a meaningless tribal ritual. Lady 
Mary suspected that this annual event held the secret to their immunity from smallpox. 

Village families would decide if anyone in the family should have smallpox that year. 
An old woman arrived carrying a nutshell full of infected liquid. She would open one of the 
volunteer’ s veins with a needle dipped in the liquid, as the family sang and chanted. The in- 
fected person stayed in bed for two to three days with a mild fever and a slight rash. He or 
she was then as well as before, never getting a serious case of smallpox. Mary wondered if 
English populations could be protected by ingrafting. 


53 



54 Vaccinations 


Upon her return to England in 1 7 1 3 , Lady Mary lectured about the potential of ingraft- 
ing. She was dismissed as an untrained and “silly” woman. In early 1714 Caroline, Princess 
of Wales, heard one of Lady Mary’s talks and approved Lady Mary’s ingrafting of convicts 
and orphans. 

Lady Mary collected the puss from smallpox blisters of sick patients and injected small 
amounts of the deadly liquid into her test subjects. The death rate of those she inoculated 
was less than one-third that of the general public, and five times as many of her subjects got 
mild, non-scarring cases. 

However, there was a problem with ingrafting. Inoculations with live smallpox viruses 
were dangerous. Some patients died from the injections that were supposed to protect them. 

Enter Edward Jenner, a young English surgeon, in 1794. Living in a rural community, 
Jenner noticed that milkmaids almost never got smallpox. However, virtually all milkmaids 
did get cowpox, a disease that caused mild blistering on their hands. Jenner theorized that 
cowpox must be in the same family as smallpox and that getting mild cowpox was like in- 
grafting and made a person immune to the deadly smallpox. 

He tested his theory by injecting 20 children with liquid taken from the blisters of a 
milkmaid with cowpox. Each infected child got cowpox. Painful blisters formed on their 
hands and arms, lasting several days. 

Two months later, Jenner injected live smallpox into each of his test children. If Jen- 
ner’ s theory was wrong, many of these children would die. However, none of his test chil- 
dren showed any sign of smallpox. 

Jenner invented the word “ vaccination ” to describe his process when he announced his 
results in 1798. Vacca is the Latin word for cow; vaccinia is Latin for cowpox. 


Asimov, Isaac. Asimov’s Chronology of Science and Discovery. New York: Haiper & 
Row, 1989. 

Clark, Donald. Encyclopedia of Great Inventors and Discoveries. London: Marshall 
Cavendish Books, 1993. 

Dyson, James. A History of Great Inventions. New York: Carroll & Graf Publishers, 


Haven, Kendall, and Donna Clark. 100 Most Popular Scientists for Young Adults. 
Englewood, CO: Libraries Unlimited, 1999. 

Vare, Ethlie Ann, and Greg Ptacek. Mothers of Invention. New York: William Mor- 
row, 1989. 



V, Fun Facts: The World Health Organization declared smallpox eradi- 
/ cated in 1979, and the President George H. Bush said that since then au- 
' thorities have not detected a single natural case of the disease in the 
world. 


More to Explore 


2001 . 


Yenne, Bill. 100 Inventions That Shaped World History. New York: Bluewood Books, 
1993. 


Infrared and Ultraviolet 

Years of Discovery: 1800 and 1801 


What Is It? Energy is radiated by the sun and other stars outside of the narrow 
visible spectrum of colors. 

Who Discovered It? Frederick Herschel (IR) and Johann Ritter (UV) 


Why Is This One of the 100 Greatest? 

Infrared and ultraviolet radiation are key parts of our scientific development over the 
past 200 years. Yet until 1 800 it never occurred to anyone that radiation could exist outside 
the narrow band that human eyes detect. The discovery of infrared and ultraviolet light ex- 
panded science’s view beyond the visible light to the whole radiation spectrum, from radio 
waves to gamma rays. 

Infrared (IR) radiation has been key to many astronomical discoveries. In addition, 
earth science uses IR to measure heat in studies of everything from ocean temperatures to 
forest health. IR sensors power burglar alarms, fire alarms, and police and fire infrared de- 
tectors. Biologists have discovered that many birds and insects detect IR radiation with their 
eyes. Ultraviolet light (UV) led to a better understanding of solar radiation and to high-en- 
ergy parts of the spectrum, including X-rays, microwaves, and gamma rays. 


How Was It Discovered? 

Frederick Herschel was born in Hanover, Germany, in 1738. As a young man, he grew 
into a gifted musician and astronomer. It was Herschel who discovered the planet Uranus in 
1781, the first new planet discovered in almost 2,000 years. 

In late 1799 Herschel began a study of solar light. He often used color filters to isolate 
parts of the light spectrum for these studies and noted that some filters grew hotter than oth- 
ers. Curious about this heat in solar radiation, Herschel wondered if some colors naturally 
carried more heat than others. 

To test this idea, Herschel built a large prism. In a darkened room, he projected the 
prism’s rainbow light spectrum onto the far wall and carefully measured the temperature in- 
side each of these separate colored light beams. 

Herschel was surprised to find that the temperature rose steadily from violet (coolest) 
to a maximum in the band of red light. On a sudden impulse, Herschel placed a thermometer 
in the dark space right next to the band of red light (just beyond the light spectrum). 

This thermometer should have stayed cool. It was not in any direct light. But it didn’t. 
This thermometer registered the most heat of all. 

55 



56 Infrared and Ultraviolet 


Herschel was amazed. He guessed that the sun radiated heat waves along with light 
waves and that these invisible heat rays refract slightly less while traveling through a prism 
than do light rays. Over the course of several weeks, he tested heat rays and found that they 
refracted, reflected, bent, etc., exactly like light. Because they appeared below red light, 
Herschel named them infrared (meaning below red). 

Johann Ritter was born in 1776 in Germany and became a natural science philosopher. 
His central beliefs were that there was unity and symmetry in nature and that all natural 
forces could be traced back to one prime force, Urkraft. 

In 1801, Ritter read about Herschel’s discovery of infrared radiation. Ritter had 
worked on sunlight’s effect on chemical reactions and with electrochemistry (the effect of 
electrical currents on chemicals and on chemical reactions). During this work he had tested 
light’s effect on silver chloride and knew that exposure to light turned this chemical from 
white to black. (This discovery later became the basis for photography.) 

Ritter decided to duplicate Herschel’ s experiment, but to see if all colors darkened sil- 
ver chloride at the same rate. He coated strips of paper with silver chloride. In a dark room 
he repeated Herschel’ s set up. But instead of measuring temperature in each color of the 
rainbow spectrum projected on wall, Ritter timed how long it took for strips of silver chlo- 
ride paper to turn black in each color of the spectrum. 

He found that red hardly turned the paper at all. He also found that violet darkened pa- 
per the fastest. 

Again mimicking Herschel’ s experiment, Ritter placed a silver chloride strip in the 
dark area just beyond the band of violet light. This strip blackened the fastest of all! Even 
though this strip was not exposed to visible light, some radiation had acted on the chemicals 
to turn them black. 

Ritter had discovered radiation beyond violet (ultraviolet) j ust as Herschel had discov- 
ered that radiation existed below the red end of the visible spectrum (infrared). 

Fun Facts: A TV remote control uses infrared light to adjust the volume 
or change the channel. 

More to Explore 

Herschel, Frederick. Preliminary Discourse on the Study of Natural Philosophy. Do- 
ver, DE: Adamant Media, 2001. 

. Treatise on Astronomy. Dover, DE: Adamant Media, 2001. 

Herschel, John. Aspects of the Life and Thought of Sir John Frederick Herschel. New 
York: Arno Press, 1994. 

Kaufl, Hans. High Resolution Infrared Spectroscopy in Astronomy. New York: 
Springer-Verlag, 2003. 

Robinson, Michael. Ripples in the Cosmos. Collingdale, PA: Diane Publishing, 2000. 


Year of Discovery: 1801 


Anesthesia 


What Is It? A medication used during surgery that causes loss of awareness of 
pain in patients. 

Who Discovered It? Humphry Davy 


Why Is This One of the 100 Greatest? 

Anesthesia created safe surgery and made many medical and dental operations practi- 
cal and plausible. The trauma suffered by patients from the pain of an operation was often so 
dangerous that it kept doctors from attempting many surgical procedures. That pain also 
kept many severely ill patients from seeking medical help. 

Anesthesia eliminated much of the pain, fear, anxiety, and suffering for medical and 
dental patients during most procedures and gave the medical profession a chance to develop 
and refine the procedures that would save countless lives. 

Anesthesiology is now a major medical specialty and an important position in every 
operating room. While it is probable that new drugs and new types of anesthesia will be de- 
veloped in the coming decades, this important aspect of medicine will be with us forever. 


How Was It Discovered? 

The word anesthesia, from the Greek words meaning “lack of sensation,” was coined by 
Oliver Wendell Holmes (father of the supreme court chief justice by the same name) in 1846. 
However, the concept of anesthesia is millennia old. Ancient Chinese doctors developed acu- 
puncture techniques that blocked the transmission of pain sensations to the brain. Ancient 
Romans and Egyptians used mandrake (the root of the mandragora plant) to induce uncon- 
sciousness. European doctors in the middle ages also favored mandrake. Inca shamans chewed 
coca leaves and spit the juice (cocaine) into wounds and cuts to numb their patients’ pain. 

Three nineteenth-century scientists each laid claim to the medical discovery of modem anes- 
thesia. None of them deserves the credit because Humphry Davy had already earned that distinction. 

Scottish obstetrician Sir Young Simpson was the first to experiment with chloroform. 
He observed that patients who inhaled a few breaths of the gas (a wad of cotton soaked in 
chloroform was placed under the nose) quickly became relaxed and calm, and were soon 
unconscious. His use of the drug drew no attention until, in 1838, Queen Victoria asked for 
Simpson and his chloroform for the birth of her seventh child. 

Chloroform’s greatest use came during the American Civil War. Southern cotton was 
often traded in England for medicines — including chloroform — that became a staple of 

57 



58 Anesthesia 


battlefield operating tents for Southern doctors. After the war, chloroform continued to en- 
joy some popularity — especially in the South — until synthetic drugs were developed in the 
early twentieth century. 

Georgia physician Crawford Long was the first to use ether during an operation. In 
1 842 he removed a neck tumor from James Venable, a local judge. The operation went per- 
fectly and the judge felt no pain. But Long never bothered to publicize his success. 

Two years later Boston dentist Horace Wells took up the notion of using ether to dull op- 
eration pain. Wells mistakenly turned off the gas too soon. His patient sat up and screamed. 
The crowd of observing doctors scoffed and called Well’s claims for ether a hoax. 

One year later ( 1 845), Boston dentist William Morton gave ether another try. Morton’ s 
operation went flawlessly. Only after Morton’s second successful public operation with 
ether, and only after he had published several articles touting the glories of ether, did doc- 
tors across America — and then Europe — turn to ether as their primary anesthetic. 

However, none of these men was the first to discover modern medical anesthesia. In 1801, 
English scientist Humphry Davy was experimenting with gasses when he combined nitrogen 
and oxygen to produce nitrous oxide. Davy tested the resulting colorless gas and eventually 
took several deep breaths. He reported a soaring euphoria that soon passed into an uncontrolla- 
ble outburst of laughter and sobbing until he passed out (it made him unconscious). 

Davy named the stuff laughing gas and noted its tendency to make him unaware of 
pain. Davy recommended it for use as an anesthetic during medical and dental procedures. 
Even though doctors took no note of his discovery, Davy’s work is the first scientific identi- 
fication and testing of an anesthetic. 


Asimov, Isaac. Asimov’s Chronology of Science and Discovery. New York: Harper & 


Row, 1989. 

Dyson, James. A History of Great Inventions. New York: Carroll & Graf Publishers, 


Fradin, Dennis. We Have Conquered Pain: The Discovery of Anesthesia. New York: 
Simon & Schuster Children’s, 1996. 

Fullmer, June. Young Humphry Davy: The Making of an Experimental Chemist. Phil- 
adelphia: American Philosophical Society, 2000. 

Galas, Judith. Anesthetics: Surgery Without Pain. New York: Thomson Gale, 1995. 

Knight, David. Humphry Davy: Science and Power. New York: Cambridge Univer- 
sity Press, 1998. 

Lace, William. Anesthetics. New York: Lucent Books, 2004. 

Radford, Ruby. Prelude to Fame: Crawford Long’s Discovery of Anaesthesia. At- 
lanta, GA: Geron-X, 1990. 



V Fun Facts: The common phrase “biting the bullet” dates from the days 
/ before anesthetics were available on the battlefield. Biting on the soft 
> lead of a bullet absorbed the pressure of the bite without damaging a sol- 
dier’ s teeth. 


More to Explore 


2001 . 


Year of Discovery: 1802 


Atoms 


What Is It? An atom is the smallest particle that can exist of any chemical 
element. 

Who Discovered It? John Dalton 


Why Is This One of the 100 Greatest? 

The modern worlds of chemistry and physics depend on knowing and studying the 
universe of atoms. But no one could actually see an atom until the invention of the electron 
microscope in 1938. Centuries before that, atoms were well known and were an important 
part of chemistry and physics research. It was John Dalton who defined the atom, allowing 
scientists to being serious study at the atomic level. An atom is the smallest particle of any 
element and the basic building block of matter. All chemical compounds are built from 
combinations of atoms. 

Since atoms are the key to understanding chemistry and physics, Dalton’ s discovery of 
the atom ranks as one of the great turning points for science. Because of this discovery, Dal- 
ton is often called the father of modern physical science. 


How Was It Discovered? 

In the fifth century B.C., Leucippus of Miletus and Democritus of Abdera theorized 
that each form of matter could be broken into smaller and smaller pieces. They called that 
smallest particle that could no longer be broken into smaller pieces an atom. Galileo and 
Newton both used the term atom in the same general way. Robert Boyle and Antoine 
Lavoisier were the first to use the word element to describe one of the newly discovered 
chemical substances. All of this work, however, was based on general philosophical theory, 
not on scientific observation and evidence. 

John Dalton was born in 1766 near Manchester, England, and received a strict Quaker 
upbringing. With little formal education, he spent 20 years studying meteorology and 
teaching at religious, college-level schools. Near the end of this period, Dalton joined, and 
presented a variety of papers to, the Philosophical Society. These included papers on the ba- 
rometer, the thermometer, the hygrometer, rainfall, the formation of clouds, evaporation, 
atmospheric moisture, and dew point. Each paper presented new theories and advanced 
research results. 

Dalton quickly became famous for his innovative thinking and shifted to science re- 
search full time. In 1801 he turned his attention from the study of atmospheric gasses to 

59 



60 Atoms 


chemical combinations. Dalton had no experience or training in chemistry. Still, he plowed 
confidently into his studies. 

By this time almost 50 chemical elements had been discovered — metals, gasses, and 
nonmetals. But scientists studying chemistry were blocked by a fundamental question they 
couldn’t answer: How did elements actually combine to form the thousands of compounds 
that could be found on Earth? For example, how did hydrogen (a gas) combine with oxygen 
(another gas) to form water (a liquid)? Further, why did exactly one gram of hydrogen al- 
ways combine with exactly eight grams of oxygen to make water — never more, never less? 

Dalton studied all of the chemical reactions he could find (or create), trying to develop 
a general theory for how the fundamental particle of each element behaved. He compared 
the weights of each chemical and the likely atomic structure of each element in each com- 
pound. After a year of study, Dalton decided that these compounds were defined by simple 
numerical ratios by weight. This decision allowed him to deduce the number of particles of 
each element in various well-known compounds (water, ether, etc.). 

Dalton theorized that each element consisted of tiny, indestructible particles that were 
what combined with other elements to form compounds. He used the old Greek word, atom, 
for these particles. But now it had a specific chemical meaning. 

Dalton showed that all atoms of any one element were identical so that any of them 
could combine with the atoms of some other element to form the known chemical com- 
pounds. Each compound had to have a fixed number of atoms of each element. Those fixed 
ratios never changed. He deduced that compounds would be made of the minimum number 
possible of atoms of each element. Thus water wouldn’t be H 4 0 0 because H 0 O was simpler 
and had the same ratio of hydrogen and oxygen atoms. 

Dalton was the first to use letter symbols (H, O, etc.) to represent the various elements. 
Scientists readily accepted Dalton’s theories and discoveries, and his concepts quickly 
spread across all Western science. We still use his concept of an atom today. 

Fun Facts: The smallest atom is the hydrogen atom, with just one elec- 
\T / tron circling a single proton. The largest naturally occurring atom is the 
(i uranium atom, with 92 electrons circling a nucleus stuffed with 92 pro- 
tons and 92 neutrons. Farger atoms have been artificially created in the 
lab but do not occur naturally on earth. 

More to Explore 

Greenway, Frank. John Dalton and the Atom. Ithaca, NY: Cornel University Press, 
1997. 

Fewis, Spencer. The Mystery of John Dalton and His Alchemy Laws. Whitefish, MT: 
Kessinger, 2005. 

Millington, J. John Dalton. Fondon: AMS Press, 1996. 

Patterson, Elizabeth. John Dalton and the Atomic Theory: The Biography of a Natural 
Philosopher. New York: Doubleday, 1996. 

Smith, Robert. Memoir of John Dalton and History of the Atomic Theory Up to His 
Time. Dover, DE: Adamant Media, 2005. 

Smyth, A. F. John Dalton: 1766-1844. New York: Dover, 1998. 


Electrochemical Bonding 

Year of Discovery: 1806 


What Is It? Molecular bonds between chemical elements are electrical in 
nature. 

Who Discovered It? Humphry Davy 


Why Is This One of the 100 Greatest? 

Davy discovered that the chemical bonds between individual atoms in a molecule are 
electrical in nature. We now know that chemical bonds are created by the sharing or transfer 
of electrically charged particles — electrons — between atoms. In 1 800, the idea that chemis- 
try somehow involved electricity was a radical discovery. 

Davy’s discovery started the modern field of electrochemistry and redefined science’s 
view of chemical reactions and how chemicals bond together. Finally, Davy used this new 
concept to discover two new (and important) elements: sodium and potassium. 


How Was It Discovered? 

Humphry Davy was born in 1778 along the rugged coast of Cornwall, England. He re- 
ceived only minimal schooling and was mostly self-taught. As a young teenager, he was ap- 
prenticed to a surgeon and apothecary. But the early writings of famed French scientist 
Antoine Lavoisier sparked his interest in science. 

In 1798 Davy was offered a chance by wealthy amateur chemist Thomas Beddoes to 
work in Bristol, England, at a new lab Beddoes built and funded. Davy was free to pursue 
chemistry-related science whims. He experimented with gases in 1799, thinking that the 
best way to test these colorless creations was to breathe them. He sniffed nitrous oxide 
(N 2 0) and passed out, remembering nothing but feeling happy and powerful. After he re- 
ported its effect, the gas quickly became a popular party drug under the name “laughing 
gas.” Davy used nitrous oxide for a wisdom tooth extraction and felt no pain. Even though 
he reported this in an article, it was another 45 years before the medical profession finally 
used nitrous oxide as its first anesthetic. 

Davy also experimented with carbon dioxide. He breathed it and almost died from car- 
bon dioxide poisoning. A bom showman, movie-star handsome, and always fashionably 
dressed, Davy delighted in staging grand demonstrations of each experiment and discovery 
for thrilled audiences of public admirers. 


61 



62 Electrochemical Bonding 


In 1799, Italian Alessandro Volta invented the battery and created the world’s first 
man-made electrical current. By 1 803, Davy had talked Beddoes into building a giant “Vol- 
taic Pile” (battery) with 110 double plates to provide more power. 

Davy turned his full attention to experimenting with batteries. He tried different metals 
and even charcoal for the two electrodes in his battery and experimented with different liq- 
uids (water, acids, etc.) for the liquid (called an electrolyte) that filled the space around the 
battery’s plates. 

In 1805 Davy noticed that a zinc electrode oxidized while the battery was connected. 
That was a chemical reaction taking place in the presence of an electrical current. Then he 
noticed other chemical reactions taking place on other electrodes. Davy realized that the 
battery (electric current) was causing chemical reactions to happen. 

As he experimented with other electrodes, Davy began to realize the electrical nature 
of chemical reactions. He tried a wide variety of materials for the two electrodes and differ- 
ent liquids for the electrolyte. 

In a grand demonstration in 1806, Davy passed a strong electric current through pure 
water and showed that he produced only two gasses — hydrogen and oxygen. Water mole- 
cules had been tom apart by an electric current. This demonstration showed that an electri- 
cal force could tear apart chemical bonds. To Davy this meant that the original chemical 
bonds had to be electrical in nature or an electric current couldn’t have ripped them apart. 

Davy had discovered the basic nature of chemical bonding. Chemical bonds were 
somehow electrical. This discovery radically changed the way scientists viewed the forma- 
tion of molecules and chemical bonds. 

Davy continued experiments, passing electrical currents from electrode to electrode 
through almost every material he could find. In 1807 he tried the power of a new battery 
with 250 zinc and copper plates on caustic potash and isolated a new element that burst into 
brilliant flame as soon as it was formed on an electrode. He named it potassium. A month 
later he isolated sodium. Davy had used his grand discovery to discover two new elements. 


Bowers, Brian, ed. Curiosity Perfectly Satisfied: Faraday’s Travels in Europe 
1813-1815. Philadelphia: Institute of Electrical Engineers, 1996. 

Davy, John, ed. Collected Works of Sir Humphry Davy. Dorset, England: Thoemmes 
Continuum, 2001. 

Fullmer, June. Young Humphry Davy: The Making of an Experimental Chemist. Phil- 
adelphia: American Philosophical Society, 2000. 

Golinski, Jan. Science as Public Culture: Chemistry and Enlightenment in Britain , 
1760-1820. New York: Cambridge University Press, 1999. 

Knight, David. Humphry Davy: Science and Power. Ames, IA: Blackwell Publishers, 



V Fun Facts: A popular use of electrochemical bonding is in cookware. 
J The process unites the anodized surface with the aluminum base, creat- 
I ing a nonporous surface that is 400 percent harder than aluminum. 


More to Explore 


1995. 


The Existence of 
Molecules 


Year of Discovery: 1811 


What Is It? A molecule is a group of attached atoms. An atom uniquely identi- 
fies one of the 1 00+ chemical elements that make up our planet. Bonding a 
number of different atoms together makes a molecule, which uniquely 
identifies one of the many thousands of substances that can exist. 

Who Discovered It? Amedeo Avogadro 


Why Is This One of the 100 Greatest? 

If atoms are the basic building block of each element, then molecules are the basic 
building blocks of each substance on Earth. Scientists were stalled by their inability to accu- 
rately imagine — let alone detect — particles as small as an atom or a molecule. Many had 
theorized that some tiny particle (that they called an atom) was the smallest possible particle 
and the basic unit of each element. However, the substances around us were not made of in- 
dividual elements. Scientists were at a loss to explain the basic nature of substances. 

Avogadro’ s discovery created a basic understanding of the relationship between all of 
the millions of substances on Earth and the few basic elements. It adjusted existing theory to 
conclude that every liter of gas (at the same temperature and pressure) had exactly the same 
number of molecules in it. This discovery allowed scientists to make critical calculations 
with and about gasses and allowed scientists to understand the nature of all substances. 
Avogadro’ s discovery (and the related Avogadro’ s Number) have become one of the cor- 
nerstones of organic and inorganic chemistry as well as the basis for the gas laws and much 
of the development of quantitative chemistry. 


How Was It Discovered? 

In the spring of 1 8 1 1 , 35-year-old college professor Amedeo Avogadro sat in his class- 
room scowling at two scientific papers laid out on his desk. Avogadro taught natural science 
classes at Vercelli College in the Italian mountain town of Turin. Twenty-five students sat 
each day and listened to Professor Avogadro lecture, discuss, and quiz them on whatever 
aspects of science caught his fancy. 

This day he read these two papers to his class, claimed that he saw an important mys- 
tery in them, and challenged his students to find it. 

63 



64 The Existence of Molecules 


In the two papers, the English chemist, Dalton, and the French chemist, Gay-Lussac, 
each described an experiment in which they combined hydrogen and oxygen atoms to cre- 
ate water. Both reported that it took exactly two liters of gaseous hydrogen atoms to com- 
bine with exactly one liter of oxygen atoms to produce exactly two liters of gaseous water 
vapor. Dalton claimed that this experiment proved that water is the combination of two at- 
oms of hydrogen and one atom of oxygen. Gay-Lussac also claimed it proved that a liter of 
any gas had to contain exactly the same number of atoms as a liter of any other gas, no 
matter what gas it was. 

These studies were heralded as major breakthroughs for chemical study. But from his 
first reading, Professor Avogadro was bothered by a nagging contradiction. 

Both Dalton and Gay-Lussac started with exactly two liters of hydrogen and one liter of 
oxygen. That’s a total of three liters of gas. But they both ended with only two liters of water 
vapor gas. If every liter of every gas has to have exactly the same number of atoms, then how 
could all the atoms from three liters of gas fit into just two liters of water vapor gas? 

The Turin cathedral bell chimed midnight before the answer struck Avogadro’ s mind. 
Dalton and Gay-Lussac had used the wrong word. What if they had each substituted “a 
group of attached atoms” for atom ? 

Avogadro created the word molecule (a Greek word meaning, “to move about freely in 
a gas”) for this “group of attached atoms.” Then he scratched out equations on paper until he 
found a way to account for all of the atoms and molecules in Dalton’s and Gay-Lussac’s ex- 


If each molecule of hydrogen contained two atoms of hydrogen, and each molecule of 
oxygen contained two atoms of oxygen, then — if each molecule of water vapor contained 
two atoms of hydrogen and one atom of oxygen, as both scientists reported — each liter of 
hydrogen and each liter of oxygen would have exactly the same number of molecules as 
each of the two resulting liters of water vapor (even though they contained a different 
number of atoms) ! 

And so it was that, without ever touching a test tube or chemical experiment of any 
kind, without even a background in chemistry, Amedeo Avogadro discovered the existence 
of molecules and created the basic gas law — every liter of a gas contains the same number 
of molecules of gas. 


Adler, Robert. Science Firsts, New York: John Wiley & Sons, 2002. 

Chang, Laura, ed. Scientists at Work. New York: McGraw-Hill, 2000. 

Downs, Robert. Landmarks in Science. Englewood, CO: Libraries Unlimited, 1996. 
Haven, Kendall. Marvels of Science. Englewood, CO: Libraries Unlimited, 1994. 
Morselli, Mario. Amedeo Avogadro. New York: D. Reidel, 1995. 


periments. 



'ji Fun Facts: The smallest molecule is the hydrogen molecule — just two 
/ protons and two electrons. DNA is the largest known naturally occurring 
• molecule, with over four billion atoms — each containing a number of 
protons, neutrons, and electrons. 


More to Explore 


Electromagnetism 

Year of Discovery: 1820 


What Is It? An electric current creates a magnetic field and vice versa. 
Who Discovered It? Hans Oersted 


Why Is This One of the 100 Greatest? 

Before 1820, the only known magnetism was the naturally occurring magnetism of 
iron magnets and of lodestones — small, weak direction finders. Yet the modern world of 
electric motors and electric generating power plants is muscled by powerful electromag- 
nets. So is every hair dryer, mixer, and washing machine. Our industry, homes, and lives de- 
pend on electric motors — which all depend on electromagnetism. 

This 1820 discovery has become one of the most important for defining the shape of 
modern life. Oersted’s discovery opened the door to undreamed of possibilities for research 
and scientific advancement. It made possible the work of electromagnetic giants such as 
Andre Ampere and Michael Faraday. 


How Was It Discovered? 

Hans Oersted was born in 1777 in southern Denmark. He studied science at the univer- 
sity, but leaned far more toward philosophy. Oersted adopted the philosophy teachings of 
John Ritter, who advocated a natural science belief that there was unity in all natural forces. 
Oersted believed that he could trace all natural forces back to the Urkraft, or primary force. 
When he was finally given a science teaching position (in 1 8 1 3), he focused his research ef- 
forts on finding a way to trace all chemical reactions back to Urkraft in order to create a 
natural unity in all of chemistry. 

Research and interest in electricity mushroomed after Benjamin Franklin’s experi- 
ments with static electricity and sparks of energy created with Leyden jars. Then, in 1800, 
Volta invented the battery and the world’s first continuous flow of electric current. Electric- 
ity became the scientific wonder of the world. Sixty-eight books on electricity were pub- 
lished between 1800 and 1820. 

Only a few scientists suspected that there might be a connection between electricity 
and magnetism. In 1776 and 1777 the Bavarian Academy of Sciences offered a prize to any- 
one who could answer the question: Is there a physical analogy between electrical and mag- 
netic force? They found no winner. In 1808, the London Scientific Society made the same 
offer. Again there was no winner. 


65 



66 Electromagnetism 


In the spring of 1 820, Hans Oersted was giving a lecture to one of his classes when an 
amazing thing happened. He made a grand discovery — the only major scientific discovery 
made in front of a class of students. It was a simple demonstration for graduate-level stu- 
dents of how electric current heats a platinum wire. Oersted had not focused his research on 
either electricity or magnetism. Neither was of particular interest to him. Still, he happened 
to have a needle magnet (a compass needle) nearby on the table when he conducted his 
demonstration. 

As soon as Oersted connected battery power to his wire, the compass needle twitched 
and twisted to point perpendicular to the platinum wire. When he disconnected the battery, 
the needle drifted back to its original position. 

Each time he ran an electric current through that platinum wire, the needle snapped 
back to its perpendicular position. Oersted’s students were fascinated. Oersted seemed flus- 
tered and shifted the talk to another topic. 

Oersted did not return to this amazing occurrence for three months — until the summer 
of 1820. He then began a series of experiments to discover if his electric current created a 
force that attracted the compass needle, or repelled it. He also wanted to try to relate this 
strange force to Urkraft. 

He moved the wire above, beside, and below the compass needle. He reversed the current 
through his platinum wire. He tried two wires instead of one. With every change in the wire and 
current, he watched for the effect these changes would produce on the compass needle. 

Oersted finally realized his electric current created both an attractive and a repulsive force 
at the same time. After months of study, he concluded that an electric current created a magnetic 
force and that this force was a whole new type of force — radically different than any of the 
forces Newton had described. This force acted not along straight lines, but in a circle around the 
wire carrying an electric current. Clearly, he wrote, wires carrying an electric current showed 
magnetic properties. The concept of electromagnetism had been discovered. 

/f~^\ Fun Facts: The aurora borealis, or “northern lights,” are an electromag- 
netic phenomenon, caused when electrically charged solar particles col- 
li lide with Earth’s magnetic field. In the Southern hemisphere these 
waving curtains of light form around the south pole and are called the au- 
rora australis, or “southern lights.” 

More to Explore 

Beaumont, Lelonce. Memoir of Oersted. Washington, DC: Smithsonian Institution, 1997. 

Brain, R. M., ed. Hans Christian Oersted and the Romantic Quest for Unity. New 
York: Springer, 2006. 

Cohen, Bernard. Revolutions in Science. Cambridge, MA: Harvard University Press, 
1995. 

Dibner, Bern. Oersted and the Discovery of Electromagnetism. Cambridge, MA: 
Burndy Library, 1995. 

Oersted, Hans. The Discovery of Electromagnetism Made in the Year 1820. London: 
H. H. Theiles, 1994. 


First Dinosaur Fossil 

Year of Discovery: 1824 


What Is It? The first proof that giant dinosaurs once walked the earth. 
Who Discovered It? Gideon Mantell and William Buckland 


Why Is This One of the 100 Greatest? 

Most people (and scientists) assumed that the world and its mix of plants and animals 
had always been as it was when these scientists lived. The discovery of dinosaur fossils de- 
stroyed that belief. This discovery represented the first proof that entire groups of ancient — 
and now extinct — animals once roamed Earth. It was the first proof that massive beasts (di- 
nosaurs) much larger than anything that exists today once existed. 

This discovery was a great leap forward for the fields of archeology and paleontology 
— both in their knowledge as well as in their field techniques. Dinosaurs have proved to be 
the most dramatic of all relics from the past and have done more to acquaint the ordinary 
person with the fact of biological evolution than anything else. 


How Was It Discovered? 

People had always found fossil bones, but none had correctly identified them as extinct 
species. In 1677 Englishman Robert Plot found what 220 years later was identified as the 
end of the thighbone of a giant biped carnivorous dinosaur. Plot gained great fame when he 
claimed it was the fossilized testicles of a giant and said it proved that story giants were real. 

Science was clearly still in the dark ages until two Englishmen, working independ- 
ently, both wrote articles on their discovery of dinosaurs in 1824. They share the credit for 
discovering dinosaurs. 

In 1809 (50 years before Darwin’s discovery of evolution) English country doctor 
Gideon Mantell lived in Lewes in the Sussex district of England. While visiting a patient 
one day, Mantell’ s wife, Mary Ann, took a short stroll and then presented him with several 
puzzling teeth she had found. These massive teeth were obviously from an herbivore but 
were far too large for any known animal. Mantell, an amateur geologist, had been collecting 
fossil relics of ancient land animals for several years but could not identify these teeth. He 
returned to the site and correctly identified the rock strata as from the Mesozoic era. Thus, 
the teeth had to be many millions of years old. 

These teeth were not the first large bones Mantell had found, but they were the most 
puzzling. Mantell took them to famed French naturalist, Charles Cuvier, who thought they 
came from an ordinary rhinoceros-like animal. Mantell set the teeth aside. 

67 



68 First Dinosaur Fossil 


In 1822 Mantell came across the teeth of an iguana and realized that these teeth were 
exact miniatures of the ones he had found 13 years earlier. Combined with other large bones 
he had recovered from the site, Mantell claimed that he had discovered an ancient, giant 
reptile that he named iguanodon (“iguana-toothed”)- He eagerly published his discovery in 
1824. 

During this same period William Buckland, a professor at Oxford University, had been 
collecting fossils in the Stonesfield region of England. During an 1 822 outing he discovered 
the jaw and several thighbones of an ancient and giant creature. (It turned out to be the same 
species discovered — but not identified — by Robert Plot 150 years before.) 

Buckland determined from these bones that this monster had been a biped 
(two-legged) carnivore. From the bone structure, Buckland claimed that it belonged to the 
reptile family. Thus he named it megalosaurus (giant lizard) and published a paper on it in 
1824. With these two publications the era of dinosaurs had been discovered. 

(f~^\ Fun Facts: The word dinosaur comes from the Greek words meaning 
“terrible lizard.” Lots of dinosaurs were named after Greek words that 
H suited their personality or appearance. Velociraptor means “speedy rob- 
ber” and triceratops means “three-homed head.” 

More to Explore 

Cadbury, Deborah. Terrible Lizard: The First Dinosaur Hunters and the Birth of a 
New Science. New York: Henry Holt, 1995. 

Dean, Dennis. Gideon Mantell and the Discovery of Dinosaurs. New York: Cam- 
bridge University Press, 1999. 

Debus, Allen. Paleoimagery: The Evolution of Dinosaurs in Art. Jefferson, NC: 
McFarland & Co., 2002. 

Hartzog, Brooke. Iguanodon and Dr. Gideon Mantell. Cherry Hill, NJ: Rosen Group, 
2001 . 

Klaver, Jan. Geology and Religious Sentiment: The Effect of Geological Discoveries 
on English Society between 1829 and 1859. Amsterdam: Brill Academic 
Publishers, 1997. 

Knight, David, ed. Geology and Mineralogy Considered with Reference to Natural 
Theology. Abingdon, England: Taylor & Francis, 2003. 


Year of Discovery: 1837 


Ice Ages 


What Is It? Earth’s past includes periods of radically different climate — 
ice ages — than the mild present. 

Who Discovered It? Louis Agassiz 


Why Is This One of the 100 Greatest? 

It was a revolutionary idea: Earth’s climate had not always been the same. Every scien- 
tist for thousands of years had assumed that Earth’s climate had remained unchanging for 
all time. Then Louis Agassiz discovered proof that all Europe had once been covered by 
crushing glaciers. Earth’s climate had not always been as it was now. With that discovery, 
Agassiz established the concept of an ever-changing Earth. 

This discovery explained a number of biological puzzles that had confounded scien- 
tists for centuries. Agassiz was also the first scientist to record careful and extensive field 
data to support and establish a new theory. Agassiz’s work did much to begin the field of 
geology and our modern view of our planet’s history. 


How Was It Discovered? 

Louis Agassiz thought of himself as a field geologist more than as a college professor. 
During weeks of rambling hikes through his native Swiss Alps in the late 1820s he noticed 
several physical features around the front faces of Swiss valley glaciers. First, glaciers 
wormed their way down valleys that were “U” shaped — with flat valley bottoms. River val- 
leys were always “V” shaped. At first he thought that glaciers naturally formed in such val- 
leys. Soon he realized that the glaciers, themselves, carved valleys in this characteristic “U” 
shape. 

Next he noticed horizontal gouges and scratches in the rock walls of these glacier val- 
leys — often a mile or more in front of the actual glacier. Finally, he became aware that many 
of these valleys featured large boulders and rock piles resting in the lower end of the valley 
where no known force or process could have deposited them. 

Soon Agassiz realized that the mountain glaciers he studied must have been much big- 
ger and longer in the past and that they, in some distant past, had gouged out the valleys, car- 
ried the rocks that scored the valleys’ rock walls leaving claw-mark scratches, and 
deposited giant boulders at their ancient heads. 


69 



70 Ice Ages 


In the early 1830s Agassiz toured England and the northern European lowlands. Here, 
too, he found “U”-shaped valleys, horizontal gouges, and scratch marks in valley rock 
walls, and giant boulders mysteriously perched in the lower valley reaches. 

It looked like the signature of glaciers he had come to know from his Swiss studies. 
But there were no glaciers for hundreds of miles in any direction. By 1835, the awe-inspir- 
ing truth hit him. In some past age, all Europe must have been covered by giant glaciers. The 
past must have been radically different than the present. Climate was not always the same. 

In order to claim such a revolutionary idea, he had to prove it. Agassiz and several 
hired assistants spent two years surveying Alpine glaciers and documenting the presence of 
the telltale signs of past glaciers. 

When Agassiz released his findings in 1837, geologists worldwide were awed. Never 
before had a researcher gathered such extensive and detailed field data to support a new 
theory. Because of the quality of his field data, Agassiz’s conclusions were immediately 
accepted — even though they radically changed all existing theories of Earth’s past. 

Agassiz created a vivid picture of ice ages and proved that they had existed. But it was 
Yugoslavian physicist Milutin Milankovich, in 1920, who explained why they happened. 
Milankovich showed that Earth’s orbit is neither circular, nor does it remain the same year 
after year and century after century. He proved that Earth’s orbit oscillates between being 
more elongated and being more circular on a 40,000-year cycle. When its orbit pulled the 
earth a little farther away from the sun in winter, ice ages happened. NASA scientists con- 
firmed this theory with research conducted between 2003 and 2005. 


Agassiz, Louis. Louis Agassiz : His Life and Science. Whitefish, MT : Kessinger, 2004. 
Lee, Jeffery. Great Geographers: Louis Agassiz. New York: Focus on Geography, 


Lurie, Edward. Louis Agassiz: Life in Science. Baltimore, MD: John Hopkins Univer- 
sity Press, 1998. 

Tallcott. Emogene. Glacier Tracks. New York: Lothrop, Lee & Shepard, 2000. 

Teller, James. Louis Agassiz: Scientist and Teacher. Columbus: Ohio State University 
Press, 1997. 

Tharp, Louis. Louis Agassiz : Adventurous Scientist. New York: Little, Brown, 1995. 



T, Fun Facts: During the last ice age the North American glacier spread 
/ south to where St. Louis now sits and was over a mile thick over Minne- 
• sota and the Dakotas. So much ice was locked into these vast glaciers that 
sea level was almost 500 feet lower than it is today. 


More to Explore 


2003. 


Calories (Units of Energy) 

Year of Discovery: 1843 


What Is It? All forms of energy and mechanical work are equivalent and can 
be converted from one form to another. 

Who Discovered It? James Joule 


Why Is This One of the 100 Greatest? 

We now know that mechanical work, electricity, momentum, heat, magnetic force, 
etc., can be converted from one to another. There is always a loss in the process, but it can be 
done. That knowledge has been a tremendous help for the development of our industries 
and technologies. Only 200 years ago, the thought had not occurred to anyone. 

James Joule discovered that every form of energy could be converted into an equiva- 
lent amount of heat. In so doing, he was the first scientist to come to grips with the general 
concept of energy and of how different forms of energy are equivalent to each other. Joule’s 
discovery was an essential foundation for the discovery (40 years later) of the law of conser- 
vation of energy and for the development of the field of thermodynamics. 


How Was It Discovered? 

Born on Christmas eve, 1818, James Joule grew up in a wealthy brewing family in 
Lancashire, England. He studied science with private tutors and, at the age of 20, started to 
work in the family brewery. 

Joule’s first self-appointed job was to see if he could convert the brewery from steam 
power to new, “modern” electric power. He studied engines and energy supplies. He stud- 
ied electrical energy circuits and was fascinated to find that the electrical wires grew hot 
when current ran through them. He realized that some of the electrical energy was being 
converted into heat. 

He felt it was important for him to quantify that electrical energy loss and began exper- 
iments on how energy was converted from electricity to heat. Often he experimented with 
little regard for safety — his or others. More than once, a servant girl collapsed unconscious 
from electrical shocks during these experiments. While he never converted the brewery to 
electrical power, these experiments turned his focus to the process of converting energy 
from one form to another. 

Joule was deeply religious, and it seemed right to him that there should be a unity for 
all the forces of nature. He suspected that heat was somehow the ultimate and natural form 
for calculating the equivalence of different forms of energy. 


71 



72 Calories (Units of Energy) 


Joule turned his attention to the conversion of mechanical energy into heat. In real life 
a moving body (with the mechanical energy of momentum) eventually stopped. What hap- 
pened to its energy? He designed a series of experiments using water to measure the conver- 
sion of mechanical motion into heat. 

Two of Joule’s experiments became famous. First, he submerged an air-filled copper 
cylinder in a tub of water and measured the water temperature. He then pumped air into the 
cylinder until it reached 22 atmospheres of pressure. The gas law said that the mechanical 
work to create this increased air pressure should create heat. But would it? Joule measured a 
0.285°F rise in water temperature. Yes, mechanical energy had been converted to heat. 

Next, Joule attached paddles onto a vertical shaft that he lowered into a tub of water. 
Falling weights (like on a grandfather clock) spun the paddles through the tub’s water. This 
mechanical effort should be partially converted to heat. But was it? 

His results were inconclusive until Joule switched from water to liquid mercury. With 
this denser fluid, he easily proved that the mechanical effort was converted to heat at a fixed 
rate. Liquid was heated by merely stirring it. 

Joule realized that all forms of energy could be converted into equivalent amounts of 
heat. He published these results in 1 843 and introduced standard heat energy units to use for 
calculating these equivalences. Since then, physicists and chemists typically use these units 
and have named them joules. Biologists prefer to use an alternate unit called the calorie 
(4. 18 joules = 1 calorie). With this discovery that any form of energy could be converted 
into an equivalent amount of heat energy, Joule provided a way to advance the study of 
energy, mechanics, and technologies. 

Fun Facts: The calories on a food package are actually kilocalories, or 
J units of 1 ,000 calories. A kilocalorie is 1 ,000 times larger than the calorie 
I? used in chemistry and physics. A calorie is the amount of energy needed 
to raise the temperature of 1 gram of water 1 degree Celsius. If you burn 
up 3,500 calories during exercise, you will have burned up and lost one 
pound. However, even vigorous exercise rarely bums more than 1 ,000 
calories per hour. 

More to Explore 

Cardwell, Donald, ed. The Development of Science and Technology in Nine- 
teenth-Century Britain. London: Ashgate Publishing, 2003. 

. James Joule: A Biography. New York: St. Martin’s Press, 1997. 

Joule, James. The Scientific Papers of James Prescott Joule. Washington, DC: Schol- 
arly Press, 1996. 

Smith, Crosbie. Science of Energy. Chicago: University of Chicago Press, 1999. 

Steffens, Henry. James Prescott Joule and the Concept of Energy. Sagamore Beach, 
MA: Watson Publishing, 1999. 


Conservation of Energy 


Year of Discovery: 1847 


What Is It? Energy can neither be created nor lost. It may be converted from 
one form to another, blit the total energy always remains constant within a 
closed system. 

Who Discovered It? Hermann von Helmholtz 


Why Is This One of the 100 Greatest? 

Energy is never lost. It can change from one form to another, but the total amount of 
energy never changes. That principle has allowed scientists and engineers to create the 
power systems that run your lights and house and fuel your car. It’s called conservation of 
energy and is one of the most important discoveries in all science. It has been called the 
most fundamental concept of all nature. It forms the first law of thermodynamics. It is the 
key to understanding energy conversion and the interchangeability of different forms of en- 
ergy. When Hermann von Hemholtz assembled all of the studies and individual pieces of 
information to discover this principle, he changed science and engineering forever. 


How Was It Discovered? 

Born in 1821 in Potsdam, Germany, Hermann von Hemholtz grew up in a family of 
gold merchants. At the age of 16, he took a government scholarship to study medicine in ex- 
change for 10 years of service in the Prussian Army. Officially he studied to be a doctor at 
the Berlin Medical Institute. However, he often slipped over to Berlin University to attend 
classes on chemistry and physiology. 

While serving in the army, he developed a research specialty: proving that the work 
muscles did was derived from chemical and physical principles and not from some “unspec- 
ified vital force.” Many researchers used “vital forces” as a way to explain anything they 
couldn’t really explain. It was as if these “vital forces” could perpetually create energy out 
of nothing. 

Helmholtz wanted to prove that all muscle-driven motion could be accounted for by 
studying physical (mechanical) and chemical reactions within the muscles. He wanted to 
discredit the “vital force” theory. During this effort, he developed a deep belief in the con- 
cept of conservation of effort and energy. (No work could be created without coming from 
somewhere or lost without going somewhere.) 

He studied mathematics in order to better describe the conversion of chemical energy 
into kinetic energy (motion and work) and the conversion of physical muscle changes into 

73 



74 Conservation of Energy 


work in order to prove that all work could be accounted for by these natural, physical 
processes. 

Helmholtz was able to prove that work could not be continually produced from “noth- 
ing.” That discovery led him to form the principle of conservation of kinetic energy. 

He decided to apply this principle of conservation to a variety of different situations. 
To do that, he studied the many pieces that had been discovered by other scientists — James 
Joule, Julius Mayer, Pierre Laplace, Antoine Lavoisier, and others who had studied either 
the conversion of one form of energy into another or the conservation of specific kinds of 
energy (momentum, for example). 

Helmholtz augmented existing studies with his own experiments to show that, time 
and time again, energy was never lost. It might be converted into heat, sound, or light, but it 
could always be found and accounted for. 

In 1 847 Helmholtz realized that his work proved the general theory of conservation of 
energy: The amount of energy in the universe (or in any closed system) always remained con- 
stant. It could change between forms (electricity, magnetism, chemical energy, kinetic en- 
ergy, light, heat, sound, potential energy, or momentum), but could neither be lost nor created. 

The greatest challenge to Helmholtz’s theory came from astronomers who studied the 
sun. If the sun didn’t create light and heat energy, where did the vast amounts of energy it 
radiated come from? It couldn’t be burning it own matter as would a normal fire. Scientists 
had already shown that the sun would consume itself within 20 million years if it actually 
burned its mass to create light and heat. 

It took Helmholtz five years to realize that the answer was gravity. Slowly the sun was 
collapsing in on itself, and that gravitational force was being converted into light and heat. 
His answer was accepted (for 80 years — until nuclear energy was discovered). More impor- 
tant, the critical concept of conservation of energy had been discovered and accepted. 

(f~f | Fun Facts: Conservation of energy plus the Big Bang tell us that all of 
the energy that ever was or ever will be anywhere in the universe was 
H present at the moment of the Big Bang. All of the fire and heat burning in 
ever star, all of the fire and energy in every volcano, all of the energy in 
the motion of every planet, comet, and star — all of it was released at the 
moment of the Big Bang. Now that must have been one BIG explosion! 

More to Explore 

Cahan, David. Hermann von Helmholtz and the Foundations of Nineteenth-Century 
Science. Berkeley: University of California Press, 1996. 

, ed. Science and Culture : Popular and Philosophical Essays. Chicago: Uni- 
versity of Chicago Press, 1995. 

Hyder, David. Kant and Helmholtz on the Physical Meaning of Geometry. Berlin: 
Walter De Gruyter, 2006. 

McKendrick, John. Hermann Ludwig Ferdinand von Helmholtz. London: Longmans, 
Green & Co., 1995. 

Warren, R. M. Helmholtz on Perception. New York: John Wiley & Sons, 1998. 


Doppler Effect 

Year of Discovery: 1848 


What Is It? Sound- and light-wave frequencies shift higher or lower depend- 
ing on whether the source is moving toward or away from the observer. 

Who Discovered It? Christian Doppler 


Why Is This One of the 100 Greatest? 

The Doppler Effect is one of the most powerful and important concepts ever discov- 
ered for astronomy. This discovery allowed scientists to measure the speed and direction of 
stars and galaxies many millions of light years away. It unlocked mysteries of distant galax- 
ies and stars and led to the discovery of dark matter and of the actual age and motion of the 
universe. Doppler’s discovery has been used in research efforts of a dozen scientific fields. 
Few single concepts have ever proved more useful. Doppler’s discovery is considered to be 
so fundamental to science that it is included in virtually ah middle and high school basic 
science courses. 


How Was It Discovered? 

Austrian-born Christian Doppler was a struggling mathematics teacher — struggling 
both because he was too hard on his students and earned the wrath of parents and adminis- 
trators and because he wanted to fully understand the geometry and mathematical concepts 
he taught. He drifted in and out of teaching positions through the 1820s and 1830s as he 
passed through his twenties and thirties. Doppler was lucky to land a math teaching slot at 
Vienna Polytechnic Institute in 1838. 

By the late 1 830s, trains capable of speeds in excess of 30 mph were dashing across the 
countryside. These trains made a sound phenomenon noticeable for the first time. Never be- 
fore had humans traveled faster than the slow trot of a horse. Trains allowed people to notice 
the effect of an object’s movement on the sounds that object produced. 

Doppler intently watched trains pass and began to theorize about what caused the 
sound shifts he observed. By 1 843 Doppler had expanded his ideas to include light waves 
and developed a general theory that claimed that an object’s movement either increased or 
decreased the frequency of sound and light it produced as measured by a stationary ob- 
server. Doppler claimed that this shift could explain the red and blue tinge to the light of dis- 
tant twin stars. (The twin circling toward Earth would have its light shifted to a higher 
frequency — toward blue. The other, circling away, would shift lower, toward red.) 


75 



76 Doppler Effect 


In a paper he presented to the Bohemian Scientific Society in 1 844, Doppler presented 
his theory that the motion of objects moving toward an observer compresses sound and light 
waves so that they appear to shift to a higher tone and to a higher frequency color (blue). 
The reverse happened if the object was moving away (a shift toward red). He claimed that 
this explained the often observed red and blue tinge of many distant stars’ light. Actually, he 
was wrong. While technically correct, this shift would be too small for the instruments of 
his day to detect. 

Doppler was challenged to prove his theory. He couldn’t with light because telescopes 
and measuring equipment were not sophisticated enough. He decided to demonstrate his 
principle with sound. 

In his famed 1845 experiment, he placed musicians on a railway train playing a single 
note on their trumpets. Other musicians, chosen for their perfect pitch, stood on the station 
platform and wrote down what note they heard as the train approached and then receded. 
What the listeners wrote down was consistently first slightly higher and then slightly lower 
than what the moving musicians actually played. 

Doppler repeated the experiment with a second group of trumpet players on the station 
platform. They and the moving musicians played the same note as the train passed. Listen- 
ers could clearly hear that the notes sounded different. The moving and stationary notes 
seemed to interfere with each other, setting up a pulsing beat. 

Having proved the existence of his effect, Doppler named it the Doppler Shift. How- 
ever, he never enjoyed the fame he sought. He died in 1853 just as the scientific community 
was beginning to accept, and to see the value of, his discovery. 

Fun Facts: Doppler shifts have been used to prove that the universe is 
\Ay expanding. A convenient analogy for the expansion of the universe is a 
If loaf of unbaked raisin bread. The raisins are at rest relative to one another 
in the dough before it is placed in the oven. As the bread rises, it also ex- 
pands, making the space between the raisins increase. If the raisins could 
see, they would observe that all the other raisins were moving away from 
them although they themselves seemed to be stationary within the loaf. 
Only the dough — their “universe” — is expanding. 

More to Explore 

Diagram Group. Facts on File Physics Handbook. New York: Facts on File, 2006. 

Eden, Alec. Search for Christian Doppler. New York: Springer-Verlag, 1997. 

Gill, T. P. Doppler Effect: An Introduction to the Theory of the Effect. Chevy Chase, 
MD: Elsevier Science Publishing, 1995. 

Haerten, Rainer, et al. Principles of Doppler and Color Doppler Imaging. New York: 
John Wiley & Sons, 1997. 

Kinsella, John. Doppler Effect. Cambridge, England: Salt Publishing, 2004. 


Berm Theory 

Year of Discovery: 1856 


What Is It? Microorganisms too small to be seen or felt exist everywhere in 
the air and cause disease and food spoilage. 

Who Discovered It? Louis Pasteur 


Why Is This One of the 100 Greatest? 

Yogurt and other dairy products soured and curdled in just a few days. Meat rotted af- 
ter a short time. Cow’s and goat’s milk had always been drunk as fresh milk. The consumer 
had to be near the animal since milk soured and spoiled in a day or two. 

Then Louis Pasteur discovered that microscopic organisms floated everywhere in the 
air, unseen. It was these microorganisms that turned food into deadly, disease -ridden gar- 
bage. It was these same microscopic organisms that entered human flesh during operations 
and through cuts to cause infection and disease. Pasteur discovered the world of microbiol- 
ogy and developed the theory that germs cause disease. He also invented pasteurization, a 
simple method for removing these organisms from liquid foods. 

How Was It Discovered? 

In the fall of 1856, 38-year-old Louis Pasteur was in his fourth year as Director of Sci- 
entific Affairs at the famed Ecole Normale in Paris. It was an honored administrative posi- 
tion. But Pasteur’s heart was in pure research chemistry and he was angry. 

Many scientists believed that microorganisms had no parent organism. Instead, they 
spontaneously generated from the decaying molecules of organic matter to spoil milk and 
rot meat. Felix Pouchet, the leading spokesman for this group, and had just published a pa- 
per claiming to prove this thesis. 

Pasteur thought Pouchet’ s theory was rubbish. Pasteur’s earlier discovery that micro- 
scopic live organisms (bacteria called yeasts) were always present during, and seemed to 
cause, the fermentation of beer and wine, made Pasteur suspect that microorganisms lived 
in the air and simply fell by chance onto food and all living matter, rapidly multiplying only 
when they found a decaying substance to use as nutrient. 

Two questions were at the center of the argument. First, did living microbes really 
float in the air? Second, was it possible for microbes to grow spontaneously (in a sterile en- 
vironment where no microbes already existed)? 

Pasteur heated a glass tube to sterilize both the tube and the air inside. He plugged the 
open end with guncotton and used a vacuum pump to draw air through the cotton filter and 
into this sterile glass tube. 


77 



78 Germ Theory 


Pasteur reasoned that any microbes floating in the air should be concentrated on the 
outside of the cotton filter as air was sucked through. Bacterial growth on the filter indicated 
microbes floating freely in the air. Bacterial growth in the sterile interior of the tube meant 
spontaneous generation. 

After 24 hours the outside of his cotton wad turned dingy gray with bacterial growth 
while the inside of the tube remained clear. Question number 1 was answered. Yes, micro- 
scopic organisms did exist, floating, in the air. Any time they concentrated (as on a cotton 
wad) they began to multiply. 

Now for question number 2. Pasteur had to prove that microscopic bacteria could not 
spontaneously generate. 

Pasteur mixed a nutrient-rich bullion (a favorite food of hungry bacteria) in a large 
beaker with a long, curving glass neck. He heated the beaker so that the bullion boiled and 
the glass glowed. This killed any bacteria already in the bullion or in the air inside the 
beaker. Then he quickly stoppered this sterile beaker. Any growth in the beaker now had to 
come from spontaneous generation. 

He slid the beaker into a small warming oven, used to speed the growth of bacterial 
cultures. 

Twenty-four hours later, Pasture checked the beaker. All was crystal clear. He checked every 
day for eight weeks. Nothing grew at all in the beaker. Bacteria did not spontaneously generate. 

Pasteur broke the beaker’s neck and let normal, unsterilized air flow into the beaker. 
Seven hours later he saw the first faint tufts of bacterial growth. Within 24 hours, the surface 
of the bullion was covered. 

Pouchet was wrong. Without the original airborne microbes floating into contact with 
a nutrient, there was no bacterial growth. They did not spontaneously generate. 

Pasteur triumphantly published his discoveries. More important, his discovery gave 
birth to a brand new field of study, microbiology. 


Clark, Donald. Encyclopedia of Great Inventors and Discoveries. London: Marshall 
Cavendish Books, 1991. 

Dubos, Rene. Pasteur and Modem Science. Madison, WI: Science Tech Publishers, 1998. 
Dyson, James. A History of Great Inventions. New York: Carroll & Graf Publishers, 


Fullick, Ann. Louis Pasteur. Portsmouth, NH: Heinemann Library, 2000. 

Gogerly, Liz. Louis Pasteur. New York: Raintree, 2002. 

Silverthorne, Elizabeth. Louis Pasteur. New York: Thomson Gale, 2004. 

Smith, Linda. Louis Pasteur: Disease Fighter. Berkeley Heights, NJ: Enslow Publish- 



Fun Facts: The typical household sponge holds as many as 320 million 
/ disease-causing germs. 


More to Explore 


2001 . 


ers, 2001. 


Yount, Lisa. Louis Pasteur. New York: Thomson Gale, 1995. 


The Theory of Evolution 

Year of Discovery: 1858 


What Is It? Species evolve over time to best take advantage of their surrounding 
environment, and those species most fit for their environment survive best. 

Who Discovered It? Charles Darwin 


Why Is This One of the 100 Greatest? 

Darwin’s theory of evolution and its concept of survival of the fittest is the most funda- 
mental and important discovery of modem biology and ecology. Darwin’s discoveries are 
1 50 years old and are still the foundation of our understanding of the history and evolution 
of plant and animal life. 

Darwin’s discovery answered countless mysteries for anthropology and paleontology. 
It made sense out of the wide distribution and special design of species and subspecies on 
Earth. While it has always stirred controversy and opposition, Darwin’s theory has been 
verified and supported by mountains of careful scientific data over the past 150 years. His 
books were best sellers in his day and they are still widely read today. 


How Was It Discovered? 

Charles Darwin entered Cambridge University in 1827 to become a priest, but 
switched to geology and botany. He graduated in 1 83 1 and, at age 22, took a position as nat- 
uralist aboard the HMS Beagle bound from England for South America and the Pacific. 

The Beagle’s three-year voyage stretched into five. Darwin forever marveled at the 
unending variety of species in each place the ship visited. But it was their extended stop at 
the Pacific Ocean Galapagos Islands that focused Darwin’s wonder into a new discovery. 

On the first island in the chain he visited (Chatham Island), Darwin found two distinct 
species of tortoise — one with long necks that ate leaves from trees, and one with short necks 
that ate ground plants. He also found four new species of finches (small, yellow birds com- 
mon across much of Europe). But these had differently shaped beaks from their European 
cousins. 

The Beagle reached the third Galapagos Island (James Island) in October 1835. Here, 
right on the equator, no day or season seemed any different than any other. 

As he did every day on shore, Darwin hoisted his backpack with jars and bags for col- 
lecting samples, a notebook for recording and sketching, and his nets and traps and set off 
across the frightful landscape through twisted fields of crunchy black lava thrown up into 
giant, ragged waves. Gaping fissures from which dense steam and noxious yellow vapors 

79 



80 The Theory of Evolution 


hissed from deep in the rock blocked his path. The broken lava was covered by stunted, sun- 
burned brushwood that looked far more dead than alive. 

In a grove of trees filled with chirping birds, Darwin found his thirteenth and four- 
teenth new species of finches. Their beaks were larger and rounder than any he’d seen on 
other islands. More important, these finches ate small red berries. 

Everywhere else on Earth finches ate seeds. In these islands some finches ate seeds, 
some insects, and some berries ! More amazingly, each species of finch had a beak perfectly 
shaped to gather the specific type of food that species preferred to eat. 

Darwin began to doubt the Christian teaching that God created each species just as it 
was and that species were unchanging. He deduced that, long ago, one variety of finch ar- 
rived in the Galapagos from South America, spread out to the individual islands, and then 
adapted (evolved) to best survive in its particular environment and with its particular 
sources of food. These findings he reported in his book, A Naturalist’s Voyage on the 
Beagle. 

After his return to England, Darwin read the collected essays of economist Thomas 
Malthus, who claimed that, when human populations could not produce enough food, the 
weakest people starved, died of disease, or were killed in fighting. Only the strong survived. 
Darwin realized that this concept should apply to the animal world as well. 

He blended this idea with his experiences and observations on the Beagle to conclude 
that all species evolved to better ensure species survival. He called it natural selection. 

A shy and private man, Darwin agonized for years about revealing his theories to the 
public. Other naturalists finally convinced him to produce and publish Origin of Species. 
With that book, Darwin’s discoveries and theory of evolution became the guiding light of 
biological sciences. 

(C~f\ Fun Facts: Bats, with their ultrasonic echolocation, have evolved the 
most acute hearing of any terrestrial animal. With it, bats can detect in- 
IP sects the size of gnats and objects as fine as a human hair. 

More to Explore 

Aydon, Cyril. Charles Darwin: The Naturalist Who Started a Scientific Revolution. 
New York: Carroll & Graf, 2003. 

Bowlby, John. Charles Darwin: A New Life. New York: W. W. Norton, 1998. 

Bowler, Peter. Charles Darwin: The Man and His Influence. New York: Cambridge 
University Press, 1998. 

Browne, Janet. Charles Darwin: Voyaging. London: Jonathan Cape, 1998. 

Dennet, Daniel. Darwin ’s Dangerous Idea: Evolution and the Meanings of Life. New 
York: Simon & Schuster, 1996. 

Jenkins, Steve. Life on Earth: The Story of Evolution. New York: Houghton Mifflin, 2002. 

Mayr, Ernst. One Long Argument: Charles Darwin and the Genesis of Modern Evolu- 
tionary Thought. Cambridge, MA: Harvard University Press, 1997. 

Woram, John. Charles Darwin Slept Here. Rockville Center, NY: Rockville Press, 
2005. 


Atomic Light Signatures 


Year of Discovery: 1859 


What Is It? When heated, every element radiates light at very specific and 
characteristic frequencies. 

Who Discovered It? Gustav Kirchhoff and Robert Bunsen 


Why Is This One of the 100 Greatest? 

Twenty new elements (beginning with the discovery of cesium in 1860) were discovered 
using one chemical analysis technique. That same technique allows astronomers to determine 
the chemical composition of stars millions of light years away. It also allowed physicists to 
understand our sun’s atomic fires that produce heat and light. That same technique allows 
other astronomers to calculate the exact speed and motion of distant stars and galaxies. 

That one technique is spectrographic analysis, the discovery of Kirchhoff and Bunsen, 
which analyzes the light emitted from burning chemicals or from a distant star. They discov- 
ered that each element emits light only at its own specific frequencies. Spectrography pro- 
vided the first proof that the elements of Earth are also found in other heavenly bodies — that 
Earth was not chemically unique in the universe. Their techniques are routinely used by scien- 
tists in virtually every field of science in the biological, physical, and earth sciences. 


How Was It Discovered? 

In 1814, German astronomer Joseph Fraunhofer discovered that the sun’s energy was 
not radiated evenly in all frequencies of the light spectrum, but rather was concentrated in 
spikes of energy at certain specific frequencies. Some thought it interesting, none thought it 
important. The idea lay dormant for 40 years. 

Gustav Kirchhoff (born in 1824) was an energetic Polish physicist who barely stood 
five feet in height. Through the mid- 1850s he focused his research on electrical currents at 
the University of Breslau. In 1858, while helping another professor with a side project, 
Kirchhoff noted bright lines in the light spectrum produced by flames and recalled having 
read about a similar occurrence in Fraunhofer’s articles. Upon investigation, Kirchhoff 
found that the bright spots (or spikes) in the light from his flame studies were at the exact 
same frequency and wave lengths that Fraunhofer had detected in solar radiation. 

Kirchhoff pondered what this could mean and was struck by what turned out to be a 
brilliant insight: use a prism to separate any light beam he wanted to study into its constitu- 
ent parts (instead of peering at it through a sequence of colored glass filters as was the cus- 


81 



82 Atomic Light Signatures 


tom of the day). Kirchhoff believed that this would let him find spikes in the radiation 
coming from any burning gas. 

However, the scheme did not work well. The flame he used to heat his gasses was too 
bright and interfered with his observations. 

Enter Robert Bunsen, the German-born chemist. In 1858, 47-year-old Bunsen had 
been developing photochemistry — the study of light given off by burning elements. During 
this work, Bunsen had invented a new kind of burner in which air and gas were mixed prior 
to burning. This burner (which we still use and call a Bunsen burner) produced an extremely 
hot (over 2700°F) flame that produced very little light. 

Kirchhoff and Bunsen connected at the University of Heidelberg in 1859. Standing to- 
gether, Kirchhoff barely reached Bunsen’s shoulder. The pair combined Kirchhoff s prism 
idea with Bunsen’s burner and spent six months to design and build the first spectrograph (a 
device to burn chemical samples and use a prism to separate the light they produced into a 
spectrum of individual frequencies). 

They began to catalog the spectral lines (specific frequencies where each element radi- 
ated its light energy) of each known element and discovered that each and every element al- 
ways produced the same “signature” set of spectral lines that uniquely identified the 
presence of that element. 

Armed with this discovery and their catalog of each element’s characteristic spectral 
lines, Kirchhoff and Bunsen made the first complete chemical analysis of seawater and of 
the sun — proving that hydrogen, helium, sodium, and half-a-dozen other trace elements 
common on Earth existed in the sun’s atmosphere. This proved for the first time that Earth 
was not chemically unique in the universe. 

Kirchhoff and Bunsen had given science one of its most versatile and flexible analyti- 
cal tools and had discovered a way to determine the composition of any star with the same 
accuracy as we determine sulfuric acid, chlorine, or any other compound. 

ff~f Fun Facts: Kirchhoff and Bunsen used their spectrograph to discover 
\k/ two new elements: cesium in 1860 (they chose that name because cesium 
5 means “sky blue,” the color of its spectrograph flame) and rubidium in 
1861. This element has a bright red line in its spectrograph. Rubidium co- 
mes from the Latin word for red. 

More to Explore 

Clark, Donald. Encyclopedia of Great Inventors and Discoveries. London: Marshall 
Cavendish Books, 1991. 

Diagram Group. Facts on File Chemistry Handbook. New York: Facts on File, 2000. 

Laidler, Keith. World of Physical Chemistry. New York: Oxford University Press, 1995. 

Lomask, Milton. Invention and Technology Great Lives. New York: Charles 
Scribner’s Sons, 1994. 

Philbin, Tom. The 100 Greatest Inventions of All Time. New York: Citadel Press, 2003. 

Schwacz, Joe. The Man Behind the Burner: Robert Bunsen ’s Discoveries Changed the 
World of Chemistry in More Ways Than One. Chicago: Thomas Gale, 2005. 

Tuniz, R. J. Accelerator Mass Spectrometry. New York: CRC Press, 1998. 


Electromagnetic Radiation/ 

Radio Waves 


Year of Discovery: 1864 


What Is It? All electric and magnetic energy waves are part of the one electro- 
magnetic spectrum and follow simple mathematical rules. 

Who Discovered It? James Clerk Maxwell 


Why Is This One of the 100 Greatest? 

Throughout most of the nineteenth century, people thought that electricity, magne- 
tism, and light were three separate, unrelated things. Research proceeded from that assump- 
tion. Then Maxwell discovered that they are all the same — forms of electromagnetic 
radiation. It was a startlingly grand discovery, often called the greatest discovery in physics 
in the nineteenth century. Maxwell did for electromagnetic radiation what Newton did for 
gravity — gave science mathematical tools to understand and use that natural force. 

Maxwell unified magnetic and electrical energy, created the term electromagnetic ra- 
diation, and discovered the four simple equations that govern the behavior of electrical and 
magnetic fields. While developing these equations. Maxwell discovered that light was part 
of the electromagnetic spectrum and predicted the existence of radio waves, X-rays, and 
gamma rays. 


How Was It Discovered? 

James Clerk was born in 1831 in Edinburgh, Scotland. The family later added the 
name Maxwell. James sailed easily through his university schooling to earn top honors and 
a degree in mathematics. He held various professorships in math and physics thereafter. 

As a mathematician, Maxwell explored the world — and the universe — through mathe- 
matic equations. His chose the rings of Saturn as the subject of his first major study. 
Maxwell used mathematics to prove that these rings couldn’t be solid disks, nor could they 
consist of gas. His equations showed that they must consist of countless small, solid parti- 
cles. A century later, astronomers proved him to be correct. 

Maxwell turned his attention to gasses and studied the mathematical relationships that 
governed the motion of rapidly moving gas particles. His results in this study completely re- 
vised science’s approach to studying the relationship between heat (temperature) and gas 
motion. 


83 



84 Electromagnetic Radiation/Radio Waves 


In 1860 he turned his attention to early electrical work by Michael Faraday. Faraday 
invented the electric motor by discovering that a spinning metal disk in a magnetic field cre- 
ated an electric current and that a changing electric current also changed a magnetic field 
and could create physical motion. 

Maxwell decided to mathematically explore the relationship between electricity and 
magnetism and the “electrical and magnetic lines of force” that Faraday had discovered. 

As Maxwell searched for mathematical relationships between various aspects of electric- 
ity and magnetism, he devised experiments to test and confirm each of his results. By 1864 he 
had derived four simple equations that described the behavior of electrical and magnetic fields 
and their interrelated nature. Oscillating (changing) electrical fields (ones whose electrical cur- 
rent rapidly shifted back and forth) produced magnetic fields and vice versa. 

The two types of energy were integrally connected. Maxwell realized that electricity and 
magnetism were simply two expressions of a single energy stream and named it electromag- 
netic energy. When he first published these equations and his discoveries in an 1864 article, 
physicists instantly recognized the incredible value and meaning of Maxwell’ s four equations. 

Maxwell continued to work with his set of equations and realized that — as long as the 
electrical source oscillated at a high enough frequency — the electromagnetic energy waves 
it created could and would fly through the open air — without conducting wires to travel 
along. This was the first prediction of radio waves. 

He calculated the speed at which these electromagnetic waves would travel and found 
that it matched the best calculations (at that time) of the speed of light. From this. Maxwell 
realized that light itself was just another form of electromagnetic radiation. Because electri- 
cally charged currents can oscillate at any frequency, Maxwell realized that light was only a 
tiny part of a vast and continuous spectrum of electromagnetic radiation. 

Maxwell predicted that other forms of electromagnetic radiation along other parts of 
this spectrum would be found. As he predicted, X-rays were discovered in 1 896 by Wilhelm 
Roentgen. Eight years before that discovery, Heinrich Hertz conducted experiments fol- 
lowing Maxwell’s equations to see if he could cause electromagnetic radiation to fly 
through the air (transmit through space in the form of waves of energy). He easily created 
and detected the world’s first radio waves, confirming Maxwell’s equations and 
predictions. 



Fun Facts: Astronomers have concluded that the most efficient way of 
making contact with an intelligent civilization orbiting another star is to use 
radio waves. However, there are many natural processes in the universe that 
produce radio waves. If we could translate those naturally produced radio 
waves into sound, they would sound like static we hear on a radio. In the 
search for intelligent life, astronomers use modem computers to distinguish 
between a “signal” (possible message) and the “noise” (static). 


More to Explore 85 


More to Explore 

Campbell, Lewis. The Life of James Clerk Maxwell. Dover, DE: Adamant Media, 
2001 . 

Francis, C. W. James Clerk Maxwell: Physicist and Natural Philosopher. New York: 
Scribner’s, 1994. 

Harmon, Peter. The Natural Philosophy of James Clerk Maxwell. New York: Cam- 
bridge University Press, 2001. 

Mahon, Basil. The Man Who Changed Everything : The Life of James Clerk Maxwell. 
New York: John Wiley & Sons, 2004. 

Maxwell, James. Matter and Motion. Amherst, NY: Prometheus Books, 2002. 


Year of Discovery: 1865 


Heredity 


What Is It? The natural system that passes traits and characteristics from one 
generation to the next. 

Who Discovered It? Gregor Mendel 


Why Is This One of the 100 Greatest? 

Gregor Mendel conducted the first serious study of heredity. His findings, his meth- 
ods, and his discoveries laid the foundation for the field of genetics and the study of genes 
and heredity. The discoveries of genes, chromosomes, DNA, and the decoding of the hu- 
man genome (completed in 2003) are all direct descendents of Mendel’s work. The medical 
breakthroughs in the fights to cure dozens of diseases are offshoots of the work begun by 
Gregor Mendel. 

Finally, Mendel’s discovery, itself, provided great insights into the role of inherited 
traits and into the ways those traits are passed form generation to generation. 


How Was It Discovered? 

The wide fields and gardens of the Austrian Monastery of Bruun stretched up gently 
sloping hills surrounding the monastery complex. Tucked into one corner of the monas- 
tery’s garden complex stood a small 120-foot-by-20-foot plot. This small garden laboratory 
was used by one of the monks, Father Gregor Mendel, for his experiments on heredity; that 
is, on how individual traits are blended from an individual through successive generations 
into a population. In May 1865, he planted his sixth year of experimental pea plants. 

English scientist Charles Darwin explained evolution but hadn’t successfully ad- 
dressed how characteristics are passed down through the generations, some to dominate 
(appear) in every generation — some to randomly pop up only every now and then. That was 
what Mendel wanted to study. 

Mendel crossed a strain of tall pea plants with one of short pea plants. He produced a 
row of all tall plants. And when he planted the seeds of those tall plants he got mostly tall 
with a few short plants. The short trait returned in the second generation. 

Similarly, he crossbred yellow peas with green peas and got a generation of all yellow 
peas. But in the next generation he produced mostly yellow with a few green peas. But never 
a yellow-green. The green color trait returned but the traits never mixed. The same hap- 
pened when he crossbred smooth-skinned with wrinkled-skinned peas. 


86 



More to Explore 87 


Over six years of work, Mendel found the same pattern in every crossbreeding experi- 
ment he tried. In the second generation, one plant in four switched and showed the recessive 
trait (the trait that hadn’t showed up at all in the first generation). Always three to one. 

He knew that a plant inherited one version of each trait (or gene) from father and 
mother plants. But what if, in each pairing of traits, one trait were always stronger (domi- 
nant), and one always weaker (recessive)? Then, when the traits mixed, a first-generation 
plant would always show the dominant one (all yellow, or all tall). 

But three to one .... That happened in the second generation. Mendel realized simple 
mathematical probability said there could be four possible combinations of traits in a sec- 
ond-generation plant (either dominant or recessive trait from either father or mother plant). 
In three of those combinations at least one dominant trait would be present, and that would 
dictate what the plant became. In only one combination (recessive trait from both parents) 
would there be nothing but recessive traits present. Three to one. 

Traits did not mix. They were inherited from generation to generation and appear only 
when they are dominant in an individual plant. Traits from countless ancestors flow into 
each of us, in separate packages called “genes,” unblended for us to pass on even if a trait 
doesn’t “show” in our generation. 

It was not until 1900 that another scientist — Dutchman Hugo de Vries — realized the 
scientific value of Mendel’s great gift to the world with his insights on heredity. 

(f~\\ Fun Facts: Gregor Mendel’s concept of heredity required two parents. 
vL/ Dolly the sheep made scientific history in 1997 when she was created 
IP from the cells of a single adult sheep in a Scottish lab. She was cloned , an 
exact genetic duplicate of her mother, with no contributing gene cells 
from a father. 

More to Explore 

Bankston, John. Gregor Mendel and the Discovery of the Gene. Hockessin, DE: 
Mitchell Lane, 2004. 

Bardoe, Cheryl. Gregor Mendel: The Friar Who Grew Peas. New York: Abrams 
Books for Young Readers, 2006. 

George, Wilma. Gregor Mendel and Heredity. Wayland, England: Howe Publishers, 
1995. 

Gribben, John. Mendel in 90 Minutes. London: Constable Press, 1997. 

Haven, Kendall. Marvels of Science. Englewood, CO: Libraries Unlimited, 1995. 

Henig, Robin. The Monk in the Garden: The Lost and Found Genius of Gregor Men - 
del. New York: Houghton Mifflin, 2000. 

Yannuzzi, Della. Gregor Mendel: Genetics Pioneer. New York: Franklin Watts, 2004. 


Deep-Sea Life 


Year of Discovery: 1870 


What Is It? Eternally black, deep ocean waters are not lifeless deserts, blit sup- 
port abundant life. 

Who Discovered It? Charles Thomson 


Why Is This One of the 100 Greatest? 

Charles Thomson radically changed science’s view of deep oceans and of the require- 
ments for life in the oceans. There existed no light in the ocean depths, yet he discovered 
abundant and varied life. He proved that life can exist without light. He even proved that 
plants can thrive in the lightless depths (though it took another century before scientists fig- 
ured out how plants live without photosynthesis). 

Thomson’s discovery extended known ocean life from the thin top layer of the oceans 
into the vast depths and provided the first scientific study of the deep oceans. For his discov- 
eries, Thomson was knighted by Queen Victoria in 1877. 


How Was It Discovered? 

Charles Thomson was born in 1830 in the salt air of the Scottish coast. After college, 
he worked at various university research and teaching positions until, in 1867, he was ap- 
pointed professor of botany at the Royal College of Science in Dublin, Ireland. 

Common wisdom at the time said that, since light only penetrated the top 250 to 300 
feet of the oceans, life only existed in that same narrow top layer where light could support 
the growth of ocean plants. The deep oceans were lifeless, lightless deserts. No one both- 
ered to question the logic of this belief. Then, in early 1866, Michael Sars conducted some 
deep dredging operations off the coast of Norway as part of a cable-laying project. He 
claimed that his dredge snared fish at depths of over 1,000 feet. 

Scientists scoffed and said that his dredge must have caught the fish either on the way 
down or on the way back up. He couldn ’t have caught them at a depth that far below the 
ocean’s “life zone” because nothing could live down there. 

However, the report caught Thomson’s imagination. He began to wonder: What if liv- 
ing creatures did lurk in the vast, dark depths of the ocean? Were ocean depths the lifeless 
desert everyone imagined? Without actually going there, how could anyone really know? 

Convinced that this question was worthy of serious scientific investigation, Thomson 
persuaded the Royal Navy to grant him use of the HMS Lightning and HMS Porcupine for 


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summer dredging expeditions for three consecutive summers: 1868, 1869, and 1870. Dur- 
ing these voyages off the English and Scottish coasts, Thomson used deep sea nets and 
dredges to see what life he could find in waters over 2,000 feet deep. Most scientists thought 
that he was wasting his time and the navy’s money and would make a fool of himself. 

Over those three brief summers, Thomson made over 370 deep-sea soundings. He 
dragged his nets and dredges through the oceans at depths of up to 4,000 feet (1,250 meters) 
and consistently found the presence of life at all surveyed depths. His nets always snared a 
variety of invertebrates and fish. 

Thomson had discovered that whole populations of fish lived and thrived in the ocean 
depths where no light ever penetrated to spoil the total blackness. 

He also collected water samples from the deep, inky-black waters and found the con- 
stant presence of detritus — dead plant life that fell through the water column to reach the 
depths without being eaten. Marine animals also died and added to this rain of food to sup- 
port creatures that lived in the depths. 

Thomson found all known marine invertebrate species living at these depths as well as 
many unknown fish species. He also dredged up bottom-dwelling plants, proving that 
plants grew and thrived without sunlight. He reported his startling discoveries in his 1873 
book The Depths of the Sea — published just after Thomson set sail on the Challenger for an 
extended, five-year voyage to complete his 70,000 nautical miles of deep-sea research data 
collection that proved that deep-sea life existed in all of the world’s oceans. 

Fun Facts: The largest giant squid ever studied was 36 feet long when it 
washed up dead on a South American beach. The circular suckers on its 
If two long arms measured 2.2 inches across. Sperm whales have been 
caught with fresh scars from giant squid suckers measuring over 22 
inches across. That translates to a monster squid over 220 feet long! 
They’re out there, but no human has seen one since sailors talked of 
meeting giant sea monsters hundreds of years ago. 

More to Explore 

Collard, Sneed. The Deep-Sea Floor. Watertown, MA: Charlesbridge Publishing, 
2003. 

Gibbons, Gail. Exploring the Deep Dark Sea. New York: Little, Brown, 1999. 

Hall, Michele. Secrets of the Ocean Realm. New York: Carroll &d Graf, 1997. 

Herring, Peter. The Biology of the Deep Ocean. New York: Oxford University Press, 
2002 . 

Tyler, P. A. Ecosystems of the Deep Ocean. Chevy Chase, MD: Elsevier Science Pub- 
lishing, 2003. 

Van Dover, Cindy. Deep-Ocean Journeys: Discovering New Life at the Bottom of the 
Sea. New York: Addison Wesley, 1997. 


Periodic Chart of Elements 


Year of Discovery: 1880 


What Is It? The first successful organizing system for the chemical elements 
that compose Earth. 

Who Discovered It? Dmitri Mendeleyev 


Why Is This One of the 100 Greatest? 

When most people think of the chemical elements, they picture Mendeleyev’s Peri- 
odic Chart of the Elements. This organizational table has served as the one accepted orga- 
nizing system for the elements that make up our planet for 125 years. It is so important that 
it is taught to every student in beginning chemistry classes. It led to the discovery of new el- 
ements and has been a cornerstone of chemists’ understanding of the properties and rela- 
tionships of Earth’s elements. It has also helped in the design and conduct of chemical 
experiments and greatly sped the development of science’s understanding of the basic 
elements in the early twentieth century. 


How Was It Discovered? 

By 1867, 33-year-old Dmitri Mendeleyev had landed a position as chemistry professor 
at St. Petersburg University — a remarkable accomplishment for the youngest of 14 children 
of a Russian peasant. With an untamed thicket of hair, a wild, trailing beard, and dark, pene- 
trating eyes, Mendeleyev was called “that wild Russian” by other chemists in Europe. In 
1868 he began work on a chemistry textbook for his students. 

The question he faced in beginning the book was how to arrange and organize the 
growing list of 62 known elements so that his students could understand their characteris- 
tics. By this time, Mendeleyev had collected a hoard of data from his own work 
and — mostly — from the work of others, especially from the English chemists Newland and 
Meyers and Frenchman de Chancourtois. 

Mendeleyev sorted the elements by atomic weight; by family resemblance; by the way 
they did — or did not — combine with hydrogen, carbon, and oxygen; by the kind of salts 
they formed; by whether an element existed as a gas, liquid, or solid; by whether an element 
is hard or soft; by whether an element melts at a high or low temperature; and by the shape 
of the element’s crystals. Nothing allowed him to make sense of all 62 known elements. 

Then Mendeleyev, a skilled piano player, realized that the notes on a piano repeated at 
regular intervals. Every eighth key was a “C.” He realized that in seasons, in waves at the 


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beach, even in trees, characteristics repeat over and over after a set period of time or dis- 
tance. Why shouldn’t the same thing happen with the elements? 

He wrote each element and its various characteristics on cards and spread them across a ta- 
ble, arranging and rearranging the cards, searching for repeating patterns. He quickly found that 
every eighth element shared many family traits, or characteristics. That is, most of the time, ev- 
ery eighth element shared characteristics with the others in this family. But not always. 

Mendeleyev was again stuck. One day that summer, it struck him that it was possible 
that not all of Earth’s elements had been discovered. His chart of the elements had to allow 
for missing elements. 

He returned to his stack of cards and arranged them into rows and columns so that the 
way that the elements in each column bonded with other elements was the same, and so that 
the physical characteristics of the elements in each row were the same. 

All of the known elements fit perfectly into this two-dimensional chart. However, he 
had to leave three holes in the chart that he claimed would be filled by three as-yet-undis- 
covered elements. Mendeleyev even described what these “missing” elements would look 
like and act like based on the common traits of other elements in their row and column. All 
Europe laughed and said his predictions were the crazy ramblings of a wild fortuneteller. 

Three years later the first of Mendeleyev’s “missing” elements was discovered in Ger- 
many. The scientific community thought it an interesting coincidence. Within eight years the 
other two had also been found. All three looked and behaved just as Mendeleyev had predicted. 

Scientists around the world were amazed and called Mendeleev a genius who had un- 
locked the mysteries of the world of chemical elements. His discovery has guided chemical 
research ever since. 

(f~^\ Fun Facts: Mendeleyev’s periodic chart helped dispel the ancient alche- 
\T/ mist’s myth of turning lead into gold. In 1980, American scientist Glenn 
• Seaborg used a powerful cyclotron to remove protons and neutrons from 
several thousand atoms of lead (atomic number 82), changing it into gold 
(atomic number 79). No, he didn’t create instant wealth. The process is so 
expensive that each atom of gold he created cost as much as several 
ounces of gold on the open market. 

More to Explore 

Atkins, P. The Periodic Kingdom. New York: Weidenfeld and Nicolson, 1999. 

. Periodic Kingdom: A Journey into the Land of the Chemical Element. New 

York: Basic Books, 1997. 

Gordon, Michael. A Well-Ordered Thing: Dmitri Mendeleev and the Shadow of the 
Periodic Table. Jackson, TN: Basic Books, 2004. 

Jensen, William, ed. Mendeleev on the Periodic Law. New York: Dover, 2005. 

Strathern, Paul. Mendeleyev’s Dream: The Quest for the Elements. New York: St. 
Martin’s Press, 2001. 

Zannos, Susan. Dmitri Mendeleev and the Periodic Table. Hockessin, DE: Mitchell 
Lane, 2004. 


Cell Division 


Year of Discovery: 1882 


What Is It? The process by which chromosomes split so that cells can divide to 
produce new cells. 

Who Discovered It? Walther Flemming 


Why Is This One of the 100 Greatest? 

Chromosomes carry genes that hold the blueprints for building, operating, and main- 
taining the cells of your body. Genetics and heredity research could not advance until these 
physical structures inside the nucleus of each cell had been discovered and studied. Our ba- 
sic understanding of biology also depends, in part, on our knowledge of how cells divide, 
replicating themselves countless times over the course of an organism’ s life. 

Both of these key concepts were discovered during one experiment carried out by 
Walther Flemming. His discoveries form part of the basic foundation of modern biological 
sciences. Much of what we know today about cell division (called mitosis ) originated with 
Flemming’s discoveries. 


How Was It Discovered? 

For most of the nineteenth century, studies of cells, cell functions, and cell structure 
through the microscope were hampered because cell walls and all of their internal parts 
were translucent to transparent. No matter how good the microscope was, these inner struc- 
tures were seen only as vague grey-on-grey shapes. It was difficult — if not impossible — to 
make out any detail. 

So scientists stained the cells with dyes, hoping to make the cell parts more visible. 
However, all dyes killed the cells. But there was no other way and, hopefully, the dye would 
combine with some intracellular structures and not with others so that a few would stand out 
and be easily studied through the microscope. Most dyes, however, didn’t work. They 
smeared the whole cell with dark color and masked the very structures they were supposed 
to reveal. 

Walther Flemming was born in 1843 in Sachsenberg, Germany. He trained as a doctor 
and taught at universities from 1873 (at the age of 30) until 1905 (age 62). He called himself 
an anatomist and specialized in the microscopic study of cells. 


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More to Explore 93 


In 1879 Flemming found a new dye (a by-product of coal tar) that combined well with 
particular, stringlike materials inside the cell nucleus and did not stain most other cell parts. 
Finally, a dye existed that allowed him to focus his observations on one particular structure 
within the cell’s nucleus. 

He named the material stained by this dye chromatin (from the Greek word for color) 
and began a series of experiments using salamander embryos. Flemming cut tissue-paper 
thin slices of embryonic cells from fertilized salamander eggs and stained them with this 
dye. 

The dye, of course, killed the cells. This stopped all cell activity and cell division. But 
it was a price Flemming had to pay in order to study these chromatin structures within the 
cell nucleus. Since the cells were dead before he could observe them, what Flemming saw 
through his microscope was a series of “still” images of cells frozen in various stages of di- 
vision. Over time, and with enough samples to study, he was able to arrange these images in 
order to show the steps of the cell division process. 

As the process began, the chromatin collected into short, threadlike objects (whose 
name Flemming changed from chromatin to chromosomes from the Greek words meaning 
“colored bodies”). It was soon clear to Flemming that these threadlike chromosomes were a 
key feature of cell division. Therefore, Flemming named the process mitosis, from the 
Greek word for thread. The words chromosomes and mitosis are still used today. 

Flemming saw that the next step was for each individual chromosome thread to break 
into two identical threads, doubling the number of chromosomes. These two identical sets 
of chromosomes then pulled apart, half going to one end of the cell, half going to the other. 
The cell itself then divided. Each of the two offspring cells was thus stocked with a com- 
plete set of chromosomes that was identical to the original parent. 

Flemming had discovered the process of cell division and published his results in 
1882. The real value of Flemming’s discovery lay hidden for 18 years. Then, in 1900, Hugo 
deVries put Flemming’s discovery together with Gregor Mendel’s discoveries on heredity 
and realized that Flemming had discovered how hereditary traits were passed from parent to 
child and from cell to cell. 

Fun Facts: Like ah living species, humans grow from a single egg cell 
into complex organisms with trillions of cells. Louise Brown, born July 
<P 25, 1978, in Oldham, England, was the first human test-tube baby. Her 
first cell divisions took place not in her mother’s womb, but in a labora- 
tory test tube. 

More to Explore 

Adler, Robert. Medical Firsts. New York: John Wiley & Sons, 2004. 

Alberts, Bruce. Molecular Biology of the Cell. Abingdon, England: Taylor & Francis, 
1999. 

Boorstin, Daniel. The Discoverers: A History of Man ’s Search to Know His World and 
Himself. New York: Random House, 1997. 


94 Cell Division 


Enslow, Sharyn, ed. Dynamics of Cell Division. New York: Oxford University Press, 
1998. 

Larison, L. L. The Center of Life: A Natural History of the Cell. New York: New York 
Times Book Co., 1997. 

Snedden, Robert. Cell Division and Genetics. Portsmouth, NH: Heinemann, 2002. 


Year of Discovery: 1895 


X-Rays 


What Is It? High-frequency radiation that can penetrate through human flesh. 
Who Discovered It? Wilhelm Roentgen 


Why Is This One of the 100 Greatest? 

If you have ever had an X-ray as part of a medical checkup, you owe thanks to Wil- 
helm Roentgen. Medical X-rays have been one of the most powerful, useful, and life-saving 
diagnostic tools ever developed. X-rays were the first noninvasive technique developed to 
allow doctors to see inside the body. X-rays led to the more modem MRI and CT 
technologies. 

Chemists have used X-rays to understand and decipher the structure of complex mole- 
cules (such as penicillin) and to better understand the electromagnetic spectrum. The dis- 
covery of X-rays earned Roentgen the 1901 Nobel Prize in physics. 


How Was It Discovered? 

In 1895 Wilhelm Roentgen was just a 40-something academic professor at the Univer- 
sity of Wurzburg, Germany, doing ho-hum research into the effects of passing electricity 
through gas-filled bottles. In November of that year he began experiments in his home base- 
ment lab with a Crookes’ tube (a device that amplified an electrical signal by passing it 
through a vacuum). 

On November 8, he happened to notice that a photographic plate that had been 
wrapped in black paper and tucked inside a leather case in the bottom drawer of his desk had 
mysteriously been exposed and imprinted with the image of a key. The only key in the room 
was an oversized key for a garden gate he had tossed into the desk’s center drawer over a 
year ago. The image on his photographic plate was of that key. 

Even more strange, he found that the key in the center drawer lay along a straight line 
from his glass Crookes' tube mounted on the wall to the photographic plate deep in the bot- 
tom drawer. But no visible rays emitted from the Crookes’ tube and surely no light could 
have penetrated through the desk and leather case to the photographic plate. What could 
have mysteriously flown across the room and passed through wood, leather, and paper to 
expose the photographic plate? Whatever it was, it could not pass through the metal 
key — which was why a dark gray image of the key was outlined on his photograph. 


95 



96 X-Rays 


Other scientists theorized that rays would be emitted from a Crookes’ tube and had 
named them cathode rays after the name of one of the metal plates inside the tube. Crookes 
thought these rays might come from another world. But no one had detected, measured, or 
studied these unknown rays. 

Roentgen suspected that cathode rays had somehow exposed his film. Two weeks later 
he was able to prove the existence of these mysterious rays, which he named “X-rays” since 
“X” was used to represent the unknown. By this time, he had seen that X-rays could pass 
through wood, paper, cardboard, cement, cloth, and even most metals — but not lead. 

For this experiment, Roentgen coated a sheet of paper with barium platino-cyanide (a 
kind of fluorescent salt) and hung it on the far wall of his lab. When he connected power to 
his Crookes’ tube, the fluorescent sheet glowed a faint green. When he held an iron disk in 
front of the paper, the paper turned back to black where the iron disk blocked the X-rays. 

Roentgen was shocked to also see the outline of every bone in his hand and arm in faint 
green outlines on the fluorescent paper. When he moved a finger, the bones outlined in 
glowing green also moved. 

On seeing these first X-ray images, Roentgen’ s wife shrieked in terror and thought that 
the rays were evil harbingers of death. Roentgen, however, began six weeks of intensive 
study before releasing his results on the nature and potential of X-rays. 

Within a month Wilhelm Roentgen’ s X-rays were the talk of the world. Skeptics called 
them death rays that would destroy the human race. Eager dreamers called them miracle 
rays that could make the blind see again and could beam complex charts and diagrams 
straight into a student’s brain. 

Doctors called X-rays the answer to a prayer. 


Aaseng, Nathan. The Inventors. Minneapolis, MN: Lemer Publications, 1998. 

Claxton, Keith. Wilhelm Roentgen. London: Fleron Books, 1994. 

Dibner, Bern. Wilhelm Conrad Rontgen and the Discovery of X-Rays. New York: 
Franklin Watts, 1998. 

Esterer, Arnulf. Discoverer of X-Rays: Wilhelm Roentgen. New York: J. Messner, 
1997. 

Garcia, Kimberly. Wilhelm Roentgen and the Discovery of X-Rays. Flockessin, DE: 
Mitchell Lane, 2002. 



T, Fun Facts: The Z Machine at the Sandia National Laboratories, New 
/ Mexico, can, very briefly, produce X-rays with a power output roughly 
> equivalent to 80 times that of all of the world’s electrical generators. 


More to Explore 


Nitske, Robert. The Life of Wilhelm Conrad Rontgen , Discoverer of the X-Ray. Tucson: 
University of Arizona Press, 1996. 


Blood Types 


Year of Discovery: 1897 


What Is It? Humans have different types of blood that are not all compatible. 
Who Discovered It? Karl Lands teiner 


Why Is This One of the 100 Greatest? 

Blood was blood — or so the world thought. Then Austrian physician Karl Landsteiner 
discovered that there were four types of blood. Some could be safely mixed and some could 
not. That discovery has saved millions of lives. The day that Karl Landsteiner ’s results were 
published, blood transfusions became a safe and risk-free part of surgery. A patient’s 
chances of surviving surgical procedures greatly increased. By making surgery safer, he 
made many new surgical procedures possible and practical. 

Landsteiner’ s discovery also greatly advanced human understanding of blood struc- 
ture and blood chemistry and paved the way for a number of key medical discoveries in the 
early twentieth century. 


How Was It Discovered? 

Vienna, Austria, was a glamorous city in 1897 — as modern as any in the world. Dr. 
Karl Landsteiner worked in the University of Vienna hospital, where he conducted 
cause-of-death (post mortem) medical examinations. 

One April day that year, Landsteiner examined four patients who had died during sur- 
gery. All died for the same reason: blood agglutination (clotting). Each patient had received 
blood transfusions and died when his or her own red blood cells clumped together with red 
blood cells in the blood they were given into thick clots. 

Landsteiner had seen this often during his thousands of post mortem examinations and 
wondered why it only happened with some patients. 

That evening, Landsteiner played piano for his wife and several friends. It was the one 
thing Karl felt he did well. Most who heard him thought he should give up medicine for a 
brilliant career as a pianist. 

In the middle of a familiar piece, it suddenly occurred to Landsteiner that the answer 
had to be something in the patients’ blood. What if all blood was not the same, as everyone 
supposed? 

The next morning Landsteiner collected blood from 20 patients, wanting to see if he 
could predict which samples were safe to mix with each other. 


97 



98 Blood Types 


In long rows of test tubes, he mixed a few drops of each patient’s blood with a few 
drops of blood from every other patient. 

In his microscope, he checked to see which red blood cells clumped together, and 
which did not. Before he had checked half the test tubes under a microscope, Karl was 
stunned to find that he could easily divide the blood samples into two distinct groups. Red 
blood cells from any member of one group agglutinated (stuck to) red blood cells from ev- 
ery member of the other group. But the cells never stuck to blood cells of other members 
from the same group. 

He named these groups “A” and “B.” Not all blood was compatible. Different people’s 
blood was different! 

He continued testing and found blood samples that didn’t agglutinate with either type 
“A” or “B” red blood cells. Landsteiner realized that there must be a third group. People in 
this group could safely donate blood to anyone. He named this third blood group type “O.” 

Then he found one blood sample that agglutinated with both type A and type B blood. 
There existed a. fourth type of blood that reacted to both A and B blood, just as type O blood 
reacted to neither. 

Karl named this fourth group type “AB.” 

Blood was not all the same. There were four distinct types. Safe transfusions required a 
doctor to determine the blood types of both patient and donor. It seemed like such a simple, 
obvious idea, and yet is one that has saved millions of lives. 


Adler, Robert. Medical Firsts. New York: John Wiley & Sons, 2004. 

Eibl, M., ed. Episode Recognition Since Landsteiner’ s Discovery. New York: 
Springer, 2002. 

Haven, Kendall. Marvels of Science. Englewood, CO: Libraries Unlimited, 1995. 

Heidelberger, Michael. Karl Landsteiner: June 14, 1868-June 26, 1943. New York: 
Columbia University Press, 1995. 

Showers, Paul. A Drop of Blood. New York: Crowell Publishers, 1999. 

Speiser, Paul. Karl Landsteiner, the Discoverer of the Bloocl-Groups and a Pioneer in 
the Field of Immunology. Frankfurt, Germany: Hollineck, 1994. 



Fun Facts: Humans have four blood types (A, B, AB, and O). Cats have 
the same number of possible blood types. Cows, however, have over 


800! 


More to Explore 


Year of Discovery: 1897 


Electron 


What Is It? The first subatomic particle ever discovered. 
Who Discovered It? J. J. Thomson 


Why Is This One of the 100 Greatest? 

Atoms had never been seen. Defined as the smallest particles possible and the basic 
building blocks of all matter, they were invisibly small — in the late nineteenth century still 
more theoretical than real. How could someone claim to have found something smaller ? 
How could particles get any smaller? 

Thomson discovered the electron and proved that it existed — without ever being able 
to see or isolate one. Electrons were the first subatomic particles to be discovered, the first 
particle of matter identified that was smaller than an atom. This discovery also finally pro- 
vided some physical proof of, and description of, the basic unit that carried electricity. 
Thomson’s experiments and discovery began a new field of science — particle physics. 


How Was It Discovered? 

He was born Joseph John Thomson in December, 1856, in Manchester, England. By 
age 1 1 he had dropped his first names and used only his initials, J. J. Thomson began engi- 
neering studies at age 14 at Owens College and later brought a math and engineering back- 
ground to the study of physics. In 1884 he was appointed to chair Cambridge’s famed 
Cavendish physics lab. Thirteen years later and still at Cavendish, Thomson conducted the 
experiment that discovered the electron. 

Cathode rays were discovered by Geiman Julius Plucker in 1856. However, scientists 
couldn’t agree on what cathode rays were. A great controversy boiled: were they waves or 
were they particles? Science’s greatest minds argued back and forth. 

In 1896 Thomson decided to design experiments that would settle this dispute. He 
built a cathode ray tube and fired its mysterious rays at a metal plate. The plate picked up a 
negative charge. This proved that cathode rays had to carry a negative charge. Next, he con- 
firmed with a fluorescent-coated ruler that a magnetic field would deflect cathode rays. 
(Others had conducted this experiment.) 

Thomson attached thin metal plates inside his cathode ray tube to a battery and showed 
that an electrical field could also deflect cathode rays. (The spot that lit up on his fluorescent 
ruler shifted when he connected the battery.) 


99 



100 Electron 


Finally, Thomson built a new cathode ray tube with a thin slit through a metal plate. 
Cathode rays were channeled through this narrow slit. Beyond that metal plate he added a 
magnetic field to deflect cathode rays in one direction, followed by an electric field that 
would deflect them back in the other direction. 

Thomson knew the force these two fields created. Once he measured the amount of de- 
flection (change of direction) each force created in the stream of cathode rays, he could cal- 
culate the mass of the particles in this cathode ray stream. That would finally solve the 
mystery by identifying the specific particles. 

Fie ran his experiment and didn’t believe his results. The ratio of electric charge to par- 
ticle mass was way too big, and that meant that the mass of these particles had to be much 
smaller than any known particle. 

Fie repeated the experiment a hundred times. Fie ripped apart and rebuilt each piece of 
equipment. The results were always the same. The mass of this particle had to be less than 
1/1000 of the mass of a proton (a hydrogen atom) — one thousand times smaller than the 
smallest atom — supposedly the smallest possible particle. 

Thomson had discovered a new particle — the first subatomic particle. It took hundreds 
of demonstrations and several detailed articles before anyone believed that his new particles 
existed. 

In 1891 Irish physicist George Stoney had named the fundamental unit (particle) of 
electricity the “electron” without having any idea what that particle was like. Thomson de- 
cided to use Stoney’ s name ( electron ) for his new particle since it carried electrical current. 
In 1898 a Frenchman named Bequerel found photographic proof of the existence of sub- 
atomic particles to confirm Thomson’s discovery. 

(f~^\ Fun Facts: If an electron weighed the same as a dime, a proton would 
\k/ weigh the same as a gallon of milk 

More to Explore 

Dahl, Per. Flash of the Cathode Rays: A History of J J Thomson ’s Electron. Abingdon, 
England: Taylor & Francis, 1997. 

Davis, E. J.J. Thomson and the Discovery of the Electron. London: CRC, 1997. 

Rayleigh, D. The Life of Sir J.J. Thomson: Sometime Master of Trinity College, Cam- 
bridge. New Castle, DE: Dawsons of Pall Mall, 1996. 

Sherman, Josepha. ./. ./. Thomson & the Discovery of Electrons. Hockessin, DE: 
Mitchell Lane, 2005. 

Thompson, George. J. J. Thomson: Discoverer of the Electron. New York: Anchor 
Books, 1998. 

. J.J. Thomson and the Cavendish Laboratory in His Day. New York: 

Doubleday, 1996. 


Year of Discovery: 1898 


Virus 


What Is It? The smallest, simplest living organism and causative agent for 
many human diseases, from simple colds to deadly yellow fever. 

Who Discovered It? Dmitri Ivanovsky and Martinus Beijerinick 


Why Is This One of the 100 Greatest? 

Far smaller than cells and bacteria, viruses are the smallest life forms on Earth — so 
small they can only reproduce inside some host cell and do it by taking over control of that 
cell. Viruses are so small they easily slip through virtually any filter or trap. Their discovery 
answered many medical questions at the beginning of the twentieth century and completed 
Pasteur’s germ theory. 

Viruses cause many of the most dangerous human diseases. Until they were discov- 
ered, medical science had ground to a halt in its advance on curing these human illnesses. 
When Beijerinick discovered viruses, he actually discovered a new life form, one too small 
to be seen with any microscope other than a mighty electron microscope. 


How Was It Discovered? 

French scientist Louis Pasteur discovered germs (microscopic bacteria) and claimed 
that germs caused disease and rot. Flowever, he was never able to find a microorganism 
(germs) that caused rabies, though he tried for over a decade before giving up in 1885. It left 
a shadow of doubt over his germ theory. 

Another disease for which no one could find an identifiable causative agent was to- 
bacco mosaic disease (so called because a mosaic pattern forms on the leaves of infected 
plants). In 1892 Russian botanist Dmitri Ivanovsky decided to search for this mysterious 
agent. (It was safer to work with tobacco mosaic disease than with deadly rabies.) 
Ivanovsky mashed up infected leaves and passed the fluid through various paper and ce- 
ramic filters. These filters were supposed to trap all organisms — even the tiniest bacteria. 

However, the fluid that strained through these sets of filters could still infect healthy 
tobacco plants with mosaic disease. That meant that Ivanovsky hadn’t trapped the causative 
agent in his filters. He tried different filter materials, different treatments, and baths for the 
leaves and mashed juice. His results were always the same. Whatever caused this disease, 
Ivanovsky couldn’t trap it in a filter. 


101 



102 Virus 


Ivanovsky refused to believe that any living organism existed that was smaller than 
bacteria and so concluded that his filters were defective and would not, in fact, catch small 
bacteria. In disgust, he abandoned his project. 

In 1898 Dutch botanist Martinus Beijerinick decided to try his luck at solving the mys- 
tery of tobacco mosaic disease. He repeated Ivanovsky’s experiment and got the same re- 
sult. However, Beijerinick was quite willing to conclude that this experiment proved that 
the causative agent was something new and unknown — something much smaller than bac- 
teria. That was why it hadn’t been trapped in his filters. Beijerinick admitted that he did not 
know what it was, but he claimed that his experiment proved that it existed and that it was 
super-tiny. He named it a “virus,” the Latin word for poison. 

While this discovery was intellectually interesting to some scientists, few cared about 
a disease unique to tobacco plants. The notion of viruses received little attention from the 
medical and scientific communities. 

In 1 899 German scientist Friedrich Loeffler conducted a similar test and concluded 
that the agent responsible for foot-and-mouth disease was too tiny to be bacteria and so 
must be another virus. Two years later, in 1901, American army surgeon Walter Reed ex- 
hausted his attempts to discover the cause for yellow fever that had killed so many Ameri- 
can soldiers. Then he tested this mosquito-borne disease to see if whatever caused it was 
small enough to be a virus. It was. 

This discovery convinced the scientific world that viruses — 1/1000 the size of even a 
small bacterium — were the cause of many human ailments and had to be studied and treated 
separately from bacteria. Ivanovsky and Beijerinick discovered viruses, but it took Walter 
Reed to make the medical and scientific community pay attention. 


Fuffle, Cady. Viruses. New York: Gareth Stevens, 2003. 

Gallo, Robert. Virus Hunting: Aids, Cancer, and the Human Retrovirus : A Story of 
Scientific Discovery. New York: Basic Books, 1997. 

Kanaly , Michael. Virus Clans: A Story of Evolution. New York: Penguin Books, 1999. 

Mahy, Brian, ed. Concepts in Virology: From Ivanovsky to the Present. Abingdon, 
England: Taylor & Francis, 1996. 

van Iterson, G. Martinus Willem Beijerinck: His Life and Work. Washington, DC: Sci- 
ence Tech Publishers, 1995. 



Fun Facts: What’s the most common disease-causing virus? The com- 
/ mon group of rhinoviruses, of which there are at least 180 types. 
' Rhinoviruses cause colds and are almost universal, affecting everyone 
except for those living in the frozen wastes of Antarctica. 


More to Explore 


Mitochondria 

Year of Discovery: 1898 


What Is It? All-important parts of every cell that provide cell energy and also 
have their own separate DNA. 

Who Discovered It? Carl Benda 


Why Is This One of the 100 Greatest? 

Mitochondria are tiny energy producers in every cell. One of many tiny structures 
floating in the cell’s cytoplasm (fluid) that are collectively called organelles, mitochondria 
are considered the most important of all cell parts — besides the nucleus. 

Amazingly, mitochondria have their own separate DNA. You depend on them. They 
depend on you. And yet they are separate living organisms that have proved invaluable in 
tracking human history and evolution as well as for understanding cell operation. Their dis- 
covery in 1898 marked a great turning point for microbiology. 


How Was It Discovered? 

Englishman Robert Hooke discovered cells in 1665 when he turned his microscope 
onto a thin sliver of cork. As microscopes improved and grew in magnification power, sci- 
entists struggled to identify cells in other plant and animal tissue. 

However, technical problems slowed their progress. More powerful microscopes were 
increasingly hard to focus and provided shaip focus on smaller and smaller areas. This was 
called “chromatic aberration.” In 1841 the achromatic microscope was invented and eased 
this problem. 

Tissue samples had to be dye-stained so that individual cells (and parts of cells) would 
show up under the microscope. However, staining often damaged cells and masked the very 
cell parts it was intended to reveal. In 1871 Camino Gogli developed a staining process he 
called “black reaction.” This process finally offered scientists a chance to see the cell inte- 
rior that lay beyond cell walls. 

In 1781 abbot Felice Fontant glimpsed the nucleus of a skin cell. Scotsman Robert 
Brown named it the “nucleus” and, while studying orchids, was the one who discovered that 
the nucleus was an essential part of living cells. In 1891 Wilhelm Waldeyer discovered 
nerve cells. 

By 1895 several researchers had actually watched cells divide through their micro- 
scopes and saw that a number of tiny structures (which they called organelles) existed inside 
each cell. 


103 



104 Mitochondria 


One of these researchers was Carl Benda, born in 1 857 in southern Germany. Even as a 
youth, Benda had been fascinated by the microscopic world and was one of the first to call 
himself a microbiologist and to make a career out of studying the microscopic world. Benda 
had been swept up in the excitement of the effort to peer inside a living cell. 

By 1898 it was clear that the cell cytoplasm (the internal fluid part of a cell) was not a 
simple, homogeneous fluid. Tiny structures floated in there doing no-one -knew-what. 

During an experiment in 1898, Benda was able to make out hundreds of tiny bodies in 
the cytoplasm through the membrane of a cell. Benda thought they must be tiny pillars that 
helped hold the shape of the cell. So he named them mitochondria, from the Greek words 
meaning “threads of cartilage.” Neither he nor other scientists at the time gave mitochondria 
any significance other than that they existed and were part of the internal structure of a cell. 

By 1910 scientists were better able to glimpse through cell walls and watch living cells 
function. Many scientists suspected that mitochondria provided energy to the cell. By 1920, 
scientists had determined that mitochondria were the power plants that supplied over 90 
percent of all cell energy needs. 

In 1963 it was discovered that mitochondria had their own DNA (called mDNA). This 
was a shattering discovery and made mitochondria one of the most important parts of a liv- 
ing cell. It meant that we are really cooperating colonies of microscopic bugs. In some 
far-distant past, tiny mitochondria organisms made a deal with bigger cells. They traded en- 
ergy for protection. The mitochondria moved inside, but kept their separate DNA. That 
made these tiny substructures unique among all elements of a living body and an important 
subject for ongoing research. 

But it all started with Benda’s discovery — even though he had no idea of the ultimate 
importance of what he discovered. 

(f~f Fun Facts: Mitochondria are called the “powerhouse of the cells,” where 
all cell energy is produced. That includes the energy for you to blink your 
9 eyes, for your heart to beat, or for you to perform amazing tasks like com- 
pleting the annual race up the 1,576 steps of the Empire State Building. 
The current record holder is Belinda Soszyn (Australia) in 1996, with a 
time of 12 minutes, 19 seconds. Imagine how much energy her mito- 
chondria had to produce ! 

More to Explore 

Chance, Britton. Energy-linked Functions of Mitochondria. Washington, DC: Aca- 
demic Press, 1994. 

Daniell, Henry, ed. Molecular Biology and Biotechnology of Plant Organelles: 
Chloroplasts and Mitochondria. New York: Springer-Verlag, 2005. 

Levings, Charles. Molecular Biology of Plant Mitochondria. London: Kulwar Aca- 
demic Publishers, 1995. 

Osawa, Syozo. Evolution of the Genetic Code. New York: Oxford University Press, 
1995. 

Scheffler, Immo. Mitochondria. Dover, DE: Wiley-Liss, 1999. 


Radioactivity 

Year of Discovery: 1901 


What Is It? Atoms are not solid balls and the smallest possible particles of 
matter, but contain a number of smaller particles within them. 

Who Discovered It? Marie Curie 


Why Is This One of the 100 Greatest? 

Marie Curie’s discovery of two naturally radioactive elements, polonium and radium, 
made headline news, but her real discovery was that atoms were not small solid balls and 
that there must be even smaller particles inside them. This discovery opened the door to all 
atomic and subatomic research and even to the splitting of the atom. 

Curie carried out her research with radioactive elements before the dangers of radioac- 
tivity were understood. She suffered from ill health (radiation sickness) for most of her 
adult life. Indeed, for many years after her death, her notebooks were still highly 
radioactive. 

Marie Curie’s studies rank as one of the great turning points of science. Physics after 
Curie was completely different than before and focused on the undiscovered subatomic 
world. She cracked open a door that penetrated inside the atom and has led to most of the 
greatest advances of twentieth-century physics. 


How Was It Discovered? 

In 1 896 Marie Curie decided to complete her doctoral dissertation in a totally new 
field: radiation. It was exciting. It was something no one had ever seen or studied before. 
Scientists knew that electrically charged radiation flooded the air around uranium, but not 
much else was known. Marie used a device her husband, professor Pierre Curie, invented to 
detect electric charges around mineral samples. She named this process radioactivity and 
concluded that radioactivity was emitted from inside a uranium atom. 

Since the Curies had had no money of their own to pay for her research, and since the 
university refused to fund a woman’s graduate-level physics research, Marie scrounged for 
free lab space. She found an abandoned shed that had been used by the Biology Department 
to hold cadavers. It was unbearably hot in the summer and freezing cold in the winter, with a 
few wooden tables and chairs and a rusty old stove. 

In 1 898 Marie was given a puzzling uranium mineral ore called pitchblende, which her 
tests showed gave off more radioactive emissions than expected from the amount of ura- 


105 



106 Radioactivity 


nium it contained. She concluded that there must be another substance inside pitchblende 
that gave off the extra radiation. 

She began each test with 3.5 ounces of pitchblende. She planned to remove all of the 
known metals so that ultimately all that would be left would be this new, highly active ele- 
ment. She ground the ore with mortar and pestle, passed it through a sieve, dissolved it in 
acid, boiled off the liquid, filtered it, distilled it, then electrolyzed it. 

Over the next six months Marie and her husband, Pierre, chemically isolated and tested 
each of the 78 known chemical elements to see if these mysterious radioactive rays flowed 
from any other substance besides uranium. Most of their time was spent begging for tiny 
samples of the many elements they could not afford to buy. Oddly, each time Marie re- 
moved more of the known elements, what was left of her pitchblende was always more ra- 
dioactive than before. 

What should have taken weeks, dragged into long months because of their dismal 
working conditions. In March 1901, the pitchblende finally gave up its secrets. Marie had 
found not one, but two new radioactive elements: polonium (named after Marie’s native Po- 
land) and radium (so named because it was by far the most radioactive element yet discov- 
ered). Marie produced a tiny sample of pure radium salt. It weighed .0035 ounces — less 
than the weight of a potato chip — but it was a million times more radioactive than uranium ! 

Because the dangers of radiation were not yet understood, Marie and Pierre were 
plagued with health troubles. Aches and pains. Ulcer-covered hands. Continuous bouts of 
serious illnesses like pneumonia. Never-ending exhaustion. Finally, the radiation Marie 
had studied all her life killed her in 1934. 


Boorse, Henry, and Lloyd Motz. The Atomic Scientist: A Biographical History. New 
York: John Wiley & Sons, 1989. 

Born, Max. Atomic Physics. New York: Dover Publications, 1979. 

Dunn, Andrew. Pioneers of Science, Marie Curie. New York: The Bookwright Press, 


Keller, Mollie. Marie Curie: An Impact Biography. New York: Franklin Watts, 1982. 

McGrayne, Sharon Bertsch. Nobel Prize Women in Science: Their Lives, Struggles, 
and Momentous Discoveries. New York: Carol Publishing Group, A Birch Lane 
Press Book, 1993. 

McKown, Robin. Marie Curie. New York: G.P. Putnam’s Sons, 1971. 

Parker, Steve. Science Discoveries: Marie Curie and Radium. New York: 
HarperCollins, 1992. 

Quinn, Susan. Marie Curie: A Life. New York: Simon & Schuster, 1996. 

Reid, Robert. Marie Curie. New York: Dutton, 1998. 



U Fun Facts: Female Nobel Prize laureates accounted for only 34 out of a 
/ total of 723 prizes awarded as of 2005. Marie Curie is not only the first 
i woman to be awarded a Nobel Prize, but also one of four persons to have 
been awarded the Nobel Prize twice. 


More to Explore 


1991. 


Atmospheric Layers 


Year of Discovery: 1902 


What Is It? Earth’s atmosphere has distinct layers of air, each with unique 
temperatures, densities, humidities, and other properties. 

Who Discovered It? Leon Philippe Teisserenc de Bort 


Why Is This One of the 100 Greatest? 

What could be more basic to understanding planet Earth than to know what lies be- 
tween the surface and Earth’s center, or between the surface and outer space? Yet the twen- 
tieth century dawned with science having virtually no concept of what the atmosphere was 
like more than two miles above the earth’s surface. 

Teisserenc de Bort was the first to expand science’s knowledge into the upper reaches 
of Earth’s atmosphere. His discovery provided the first accurate image of our atmosphere 
and formed the basis for our understanding of meteorological phenomena (storms, winds, 
clouds, etc.). Teisserenc de Bort was also the first to take scientific instruments into the 
upper atmosphere. 


How Was It Discovered? 

Born in Paris in 1855, Leon Philippe Teisserenc de Bort was appointed the chief of the 
Administrative Center of National Meteorology in Paris at the age of 30. There he was frus- 
trated because he believed that science’s inability to understand and predict weather 
stemmed from lack of knowledge about the atmosphere more than three or four kilometers 
above the surface. 

Certainly, manned balloon flights (both hot air and gas filled) had carried instruments 
into the atmosphere. But these flights never ventured above four or five kilometers in alti- 
tude. There wasn’t enough oxygen up there for people to breathe. 

In 1895 Teisserenc de Bort quit his job to devote full time to developing unmanned, 
high-altitude gas balloons at his Versailles villa (outside of Paris). Over the next five years, 
Teisserenc de Bort designed an instrument package in a wicker basket that his balloons 
would carry aloft. Basic thermometers and barometers were connected to recording devices 
so that he would have written records of upper atmospheric conditions once the balloon 
returned to Earth. 

He also designed a release system and parachute to deploy after the basket released 
from the rising balloon to bring his instrument package gently back down. 


107 



108 Atmospheric Layers 


Teisserenc de Bort found that tracking the basket and parachute were more difficult 
than he first thought, even when he used a telescope. Each launch involved a mad scramble 
across the countryside to keep the descending package in sight. Even so, a few were never 
found, some sunk in rivers or lakes, and some were smashed when the parachutes failed. 

Still, Teisserenc de Bort persisted — and was amazed at what he discovered. Atmo- 
spheric temperature decreased steadily at a constant rate of 6.5°C per kilometer of altitude 
(19°F per mile). This decrease was expected. 

However, at an altitude of around 1 1 km (7 miles, or about 37,000 feet) the tempera- 
ture stopped decreasing at all. It remained level at around -53°C up to over 48,000 feet (as 
high as Teisserenc de Bort’s balloons would fly). 

At first Teisserenc de Bort didn’t believe that the temperature could possibly stop de- 
creasing. He suspected that the instruments rose to a height where solar heating warmed the 
thermometer and compensated for continued atmospheric temperature decrease. 

He began to launch at night. It was harder to track the parachute’s descent, but it pre- 
vented any possibility of solar heating. Even at night, his results were the same. The temper- 
ature above 1 1 km remained constant. 

After 234 tests, Teisserenc de Bort finally concluded that his measurements were accu- 
rate and that there were two, separate layers to the atmosphere. Near the surface lay an 
1 1-km-thick lower layer where temperature changes created currents, winds, clouds, and 
weather. Above that was a region where constant temperature allowed air to settle into 
quiet, undisturbed layers 

He named the lower layer the troposphere, from the Greek words meaning “sphere of 
change,” and the upper layer the stratosphere, from the Greek words meaning “sphere of 
layers.” 

Teisserenc de Bort’ s discovery is still the basis of our understanding of the atmosphere. 

f Fun Facts: Scientists now know that the atmosphere has many layers, 
but the troposphere is the layer where all of Earth’s weather occurs. 

More to Explore 

Emanuel, Kerry . Atmospheric Convection. New York: Oxford University Press, 1997. 

Hewitt, C. N., ed. Handbook of Atmospheric Science: Principles and Applications. 
Boston: Blackwell Publishers, 2003. 

Jones, Phil. History and Climate. London: Kluwer Academic Press, 2001. 

Parker, Sybil, ed. McGraw-Hill Encyclopedia of Ocean and Atmospheric Sciences. 
New York: McGraw-Hill, 1997. 

Stull, Ronald. Introduction to Boundary Layer Meteorology. London: Kluwer Aca- 
demic Press, 1998. 

Wallace, John. Atmospheric Science, First Edition: An Introductory Survey. New 
York: Academic Press, 1997. 


Year of Discovery: 1902 


Hormones 


What Is It? Chemical messengers that trigger action in various organs within 
the body. 

Who Discovered It? William Bayliss and Ernst Starling 


Why Is This One of the 100 Greatest? 

At the dawn of the twentieth century, scientists thought that all control signals in the 
human body were sent electrically along nerve fibers. Then Bayliss and Starling discovery 
that chemical messengers (called hormones) as well as electric signals trigger body organs 
to function. This startling discovery started a whole new field of medical science: endocri- 
nology. It revolutionized physiology and has been called one of the greatest discoveries of 
all time related to the human body. 

Once discovered and commercially produced, these hormones were hailed as miracle 
drugs when made available in the marketplace. Adrenalin (the first hormone to be discov- 
ered) was the first “blockbuster” drug of the twentieth century. Other hormones followed 
close behind. 


How Was It Discovered? 

Bayliss and Starling get credit for discovering hormones. However, we must give 
some credit to those who, several years before, actually discovered the first hormone — even 
though they did not realize the true significance of their discovery. 

During a long series of animal experiments in 1 894, British physiologist Edward Al- 
bert Shaipey-Schafer showed that fluid extracted from the adrenal gland would raise blood 
pressure if injected into an animal’s blood stream. He thought it interesting, but did not see 
any practical value to his find. In 1 898 American pharmacologist John Abel recognized the 
medical value of this substance and studied its origin and chemistry. He isolated the key 
chemical in this fluid and named it epinephrine (from the Greek words meaning “above the 
kidney,” since that’s where the adrenal gland is housed). 

Two years later, Japanese entrepreneur and chemist Jokichi Takamine set up a lab in 
New York to create a synthetic version of epinephrine in pure crystalline form that could be 
commercially produced. In 1901 he succeeded, and called it adrenaline because the natural 
chemical came from the adrenal gland. While Takamine realized the commercial value of 
his creation (and quickly patented the name and manufacturing process), he did not take 


109 



110 Hormones 


note of the biological significance of finding a chemical substance that traveled through the 
bloodstream to deliver an activation message to an organ. 

In 1902 two professors and medical researches at University College of London began 
a study of digestive juices. One was 40-year-old William Bayliss. His partner was his 
34-year-old brother-in-law, Ernst Starling. 

Medical scientists knew that the pancreas began to secrete digestive juice as soon as 
the food content in the stomach first entered the small intestine. But how did the pancreas 
know that it should begin to produce juice at that moment? All assumed an electric signal 
was somehow sent through nerve cells. Bayliss and Starling decided to test this theory. 

They cut the nerves leading to the pancreas of a laboratory dog. Yet the pancreas still 
performed on cue. Upon close examination, they found that the lining of the dog’s small in- 
testine secreted a liquid substance as soon as stomach acid reached it. This fluid (which they 
named secretin) traveled through the bloodstream to the pancreas and signaled the pancreas 
to leap into action. 

Unlike Takamine, Bayliss and Starling instantly realized that this was the first docu- 
mented case of a signal being sent chemically through the body instead of electrically along 
nerve fibers. They announced their findings, to the delight and wonder of the scientific 
community. 

Bayliss suspected that many more such chemical messengers existed and would be 
found. As soon as he read a report on Takamine’s work, Bayliss realized that Takamine had 
discovered another in this group of chemical messengers when he isolated adrenalin. 

In 1905 Starling coined the name hormones for this growing group of chemical mes- 
sengers, from the Greek words meaning “to arouse to activity.” The third hormone to be dis- 
covered was cortisone, in 1935, by American biochemist Edward Calvin. Now, almost 30 
hormones have been discovered that speed signals through your body, and their importance 
can hardly be overstated. 

Fun Facts: Robert Earl Hughes, the world’s largest man, weighed 484 
vL / kg (1,067 lb.) at his death in 1958. Years after his death, scientists discov- 
If ered that he had too little of the hormone thyroxin in his system. Without 
this vital hormone, his body couldn’t burn the food he ate, and so his 
body continually stored it as fat. 

More to Explore 

Bliss, Michael. Discovery of Insulin. Chicago: University of Chicago Press, 1994. 

Fox, Ruth. Milestones in Medicine. New York: Random House, 1995. 

Frayn, Keith. Metabolic Regulation: A Human Perspective. Boston: Blackwell Pub- 
lishers, 2003. 

Henderson, John. A Life of Ernest Starling. New York: Oxford University Press, 2004. 

Maleskey, Gale. Hormone Connection. New York: Rodale Press, 2001. 


Year of Discovery: 1905 


E = mc 2 


What Is It? The first established relationship between matter and energy. 
Who Discovered It? Albert Einstein 


Why Is This One of the 100 Greatest? 

For all of history, matter was matter and energy was energy. The two were separate, 
unrelated concepts. Then Einstein established the relationship between matter and energy 
by creating the most famous equation in the history of humankind, E = me 2 . (The second 
most famous is the Pythagorean Theorem for a right triangle, A 2 = B 2 + C 2 .) 

Einstein’s equation for the first time defined a quantified relationship between matter 
and energy. It meant that these two aspects of the universe that had always been thought of 
as separate were really interchangeable. 

This one equation altered the direction of physics research, made Michelson’s calcula- 
tion of the speed of light (1928) critical, and led directly to the nuclear bomb and nuclear en- 
ergy development. 


How Was It Discovered? 

In 1903, 24-year-old Albert Einstein landed a job as a patent clerk for the Swiss patent 
office. His whole job was to check the technical correctness of patent submissions. Though 
he had always dreamed of, and aimed for, a career in science, he had utterly failed to gain an 
entry into that world. He had failed high school and was barred from teaching. 

He had married his high school girlfriend. He was a low-level bureaucrat scraping by 
in Berne, Switzerland, and it seemed that that was all he would ever be. 

Though he had been shunned in his formal education, Einstein was still a passionate 
amateur mathematician and physicist. He spent virtually all of his free time mulling over the 
great mysteries and problems facing physicists of the day. 

Einstein worked best through what he called mind experiments. He searched for vivid 
mental images that would shed new light on, and provide a new perspective on, complex 
physics problems. Then he applied the mathematics he knew so well to explain the images 
and to understand their physics implications. 

By 1904 Einstein was attempting to extend the existing physics of the day by focusing 
on the relationships between light, space, and time. He was able to show that light exists as 
both waves and as particles. (A particle, or quanta, of light we call a photon.) 


Ill 



112 E = me 2 


This work led to Einstein’s revolutionary concept of relativity. From the mathematics 
that described this concept, he came to several startling conclusions. Time was as rubbery as 
space. It slowed down as an object sped up. Objects increase in mass as they approach 
nearer to light speed. Einstein’s theory of relativity established a direct link between space 
and time and showed that they both warp around heavy objects (like stars). Their measure- 
ment is only possible in a relative, not an absolute, sense. 

From this theoretical foundation, Einstein continued his mathematical development 
and showed that, as an object approaches the speed of light, its length decreases, its mass in- 
creases, and time slows down. (This concept was later confirmed with precision clocks car- 
ried on high-speed jet airplanes.) 

If matter changed as it sped up, then matter and energy had to be somehow related to 
each other. Einstein realized that his theory of relativity showed that matter has to be a 
highly concentrated form of energy. He suspected that he could deduce a mathematical rela- 
tionship between the two. 

Einstein realized that this revolutionary concept contradicted the famed and com- 
pletely accepted concepts of conservation of mass (Lavoisier, 1789) and conservation of 
energy (Hemholtz, 1847). Einstein was saying that these two giants of science were both 
wrong and that neither energy nor matter were independently conserved. However, com- 
bined, the total energy in this energy-matter system had to still be conserved. 

Einstein viewed the energy-matter equation he derived (E = mc : ) like frosting on the 
cake of his relativity theory. He submitted an article on it almost as an afterthought to his 
theory of relativity, as a sequel to it. To Einstein, this equation was only of interest as a 
physics and science concern, as a way to view the theoretical interchange between mass and 
energy. He did not think it was particularly important. 

Others, however, quickly realized the implications of Einstein’s equation for weapons 
design and for nuclear energy production. “The world,” said Aldous Huxley after reviewing 
Einstein’s physics, “is not only queerer than we imagine, it is queerer than we can imagine.” 


Bartusiak, Marcia. Einstein’s Unfinished Symphony: Listening to the Sounds of 
Space-Time. Washington, DC: Joseph Henry Press, 2000. 

Bernstein, Jeremy. Einstein. New York: Penguin, 1995. 

Brian, Denis. Einstein: A Life. New York: John Wiley & Sons, 1996. 

Calaprice, Alice. The Quotable Einstein. Princeton, NJ: Princeton University Press, 



V Fun Facts: Einstein’s famous equation tells us exactly how much energy 
/ exists in any given object (or mass). However, only one reaction releases 
' all of this energy: a matter-antimatter collision, the only perfect conver- 
sion of matter into energy in our universe. 


More to Explore 


1996. 


Folsing, Albrecht. Albert Einstein: A Biography. New York: Viking, 1997. 
Goldsmith, Donald. The Ultimate Einstein. New York: Byron Press, 1997. 


More to Explore 113 


Goldsmith, Maurice, ed. Einstein: the First Hundred Years. New York: Pergamon 
Press, 1996. 

Overbye, Dennis. Einstein in Love: A Scientific Romance. New York: Viking, 2000. 

Parker, Barry. Einstein ’s Dream: The Search for a Unified Theory of the Universe. 
New York: Plenum, 2000. 

Whitrow, G., ed. Einstein: The Man and His Achievements. New York: Dover Publi- 
cations, 1997. 


Year of Discovery: 1905 


Relativity 


What Is It? Einstein’s theory that space and time merge to form the fabric of 
the universe that is warped and molded by gravity. 

Who Discovered It? Albert Einstein 


Why Is This One of the 100 Greatest? 

Albert Einstein is one of only three or four scientists in history who have changed the 
fundamental ways in which humans view the universe. Einstein’s theory of relativity 
changed humankind’s core assumptions concerning the nature of the universe and of 
Earth’s and of humans’ place in it. 

The twentieth century’s developments in technology, science, and math owe their 
foundation to this unassuming scientist in a deep and fundamental way. He has touched our 
lives probably more than any other scientist in history. But for the first 26 years of his life, 
no one thought he had any chance of entering the world of science at all. 


How Was It Discovered? 

Raised in Munich, Germany, Albert Einstein showed no early signs of genius. He was 
described as a dull child who didn’t play well with other children. Grammar school teachers 
called him irksome and disruptive. At 16 he was expelled from school. Albert’s father en- 
couraged him to apply to the Polytechnic Institute in Zurich, Switzerland, and learn a trade 
to help support the family. 

But Albert failed the entrance exam. A school administrator was, however, impressed 
with Albert’s math abilities and arranged for him to complete high school in nearby Aarua, 
Switzerland. At 17, Albert transferred to Zurich. 

There he showed promise in math and science, but piled up far too many discipline re- 
ports. He was free with his opinions whether they were offensive or not. His teachers gave 
him bad reports. One called him “a lazy dog.” 

Einstein hoped to teach after graduation but his grades weren’t good enough. He 
dropped out of science in disgust and supported himself with odd jobs. In 1902 he landed a 
job as a clerk in the Swiss Patent Office, assigned to check the technical correctness of pat- 
ent applications. It appeared that all doors leading to a science career had been firmly 
closed. 


114 



More to Explore 115 


It was while riding on a Berne, Switzerland, trolley car in the spring of 1904 that the 
image first flashed across Albert Einstein’ s mind. It was an image of a man in an elevator 
that was falling from a great height. Einstein realized immediately that the image of this 
“thought experiment” could bring focus to a problem that had been plaguing him (and all of 
science) for years. 

Einstein realized that the man in the elevator would not know he was falling because, 
relative to his surroundings (the elevator), he wasn’t falling. The man — like us — would not 
be able to detect that he (and his elevator) were caught in, and being pulled by, a gravita- 
tional field. If a horizontal light beam entered the side of the elevator, it would strike the far 
wall higher up because the elevator would have dropped while the light beam crossed. To 
the man, it would appear that the light beam bent upwards. From our perspective ( relative to 
us), gravitational fields bend light. Light not only could be, but routinely was, bent by the 
gravitational fields of stars and planets. 

It was a revolutionary concept, worthy of one of the world’s greatest scientific minds. 
Einstein regularly used these imaginative “thought experiments” to shed light on complex 
questions of general principles. It was a new and unique way to approach the study of phys- 
ics and led Einstein to write a series of four papers, which he submitted to a science journal 
in 1905. One of those four papers presented the special theory of relativity (relativity princi- 
ples applied to bodies either moving at a steady velocity or at rest). Impressed, the journal 
published all four papers in a single issue. Another presented Einstein’s relation between 
matter and energy. 

The papers from this “amateur” mathematician had a deep, instant, and profound ef- 
fect in the scientific community. One was accepted as a doctoral thesis by Zurich Univer- 
sity, which granted Einstein a Ph.D. 

Virtually all physicists shifted their studies to focus on Einstein’s theories. 

In 1916, with war raging across Europe, Einstein published his general theory of rela- 
tivity, which described relativity theory applied to objects moving in more complex ways 
with nonlinear acceleration. The world applauded. 


Bartusiak, Marcia. Einstein’s Unfinished Symphony: Listening to the Sounds of 
Space-Time. Washington, DC: Joseph Henry Press, 2000. 

Bernstein, Jeremy. Einstein. New York,:Penguin, 1995. 

Brian, Denis. Einstein: A Life. New York: John Wiley & Sons, 1996. 

Calaprice, Alice. The Quotable Einstein. Princeton, NJ: Princeton University Press, 



Ti Fun Facts: We know that the look and sound of moving objects appear 
J and sound different depending on whether the receiver is stationary or 
' moving. Special relativity is based on the mind-boggling concept that, no 
matter how fast you travel, the speed of light appears to remain the same! 


More to Explore 


1996. 


Folsing, Albrecht. Albert Einstein: A Biography. New York: Viking, 1997. 
Goldsmith, Donald. The Ultimate Einstein. New York: Byron Press, 1997. 


116 Relativity 


Goldsmith, Maurice, ed. Einstein: The First Hundred Years. New York: Pergamon 
Press, 1996. 

Overbye, Dennis. Einstein in Love: A Scientific Romance. New York: Viking, 2000. 

Parker, Barry. Einstein’s Dream: The Search for a Unified Theory of the Universe. 
New York: Plenum, 2000. 

Whitrow, G., ed. Einstein: The Man and His Achievements. New York: Dover Publi- 
cations, 1997. 


Year of Discovery: 1906 


Vitamins 


What Is It? Trace dietary chemical compounds that are essential to life and 
health. 

Who Discovered It? Christiaan Eijkman and Fredrick Hopkins 


Why Is This One of the 100 Greatest? 

We label foods by their vitamin content. We spend billions of dollars every year 
buying vitamin supplements. Vitamins are essential to life and health. Yet any awareness 
of vitamins — even the very notion of vitamins — is only 100 years old. It had not occurred to 
anyone to search for trace elements in food that human bodies needed. They had only con- 
sidered measuring the amount of food and the calories in it. 

The discovery of vitamins revolutionized nutritional science and the public’s aware- 
ness of health, diet, and nutrition. It radically changed biological science and the study of 
how the human body functions. 


How Was It Discovered? 

During the early 1890s, the disease beriberi wreaked havoc on the Dutch East India 
Company’s operations in India. Since Pasteur had discovered germs, scientists assumed 
that all diseases were caused by germs. Yet Company doctors could find no germ for 
beriberi. 

In 1896, 35-year-old Dutch physician Christiaan Eijkman traveled to India to try his 
luck at the investigation. Shortly after he arrived, a massive outbreak of beriberi swept 
through the flock of chickens at the research facility used for bacteriological research. 

Eijkman began frantic research on the diseased flock when, just as suddenly, the dis- 
ease vanished. Eijkman was baffled until he interviewed the cook who fed the chickens and 
found that, just before and during the outbreak, he had switched the chickens’ feed to white 
rice intended for human consumption. When company officials had yelled at him for feed- 
ing expensive polished (white) rice to chickens, the cook had switched back to normal 
chicken feed using brown rice. 

He found that he could cause beriberi at will by switching chicken feed to white (pol- 
ished) rice and cure it by switching back. He examined local jail diets and found that where 
prisoners were fed a diet of brown rice, no beriberi occurred. In jails that used white rice, 
beriberi outbreaks were common. 


117 



118 Vitamins 


Eijkman believed that something in brown rice cured beriberi and wrote a report 
claiming victory over the disease. He never considered looked at it the other way: that beri- 
beri was caused by the absence of something that was present in brown rice. 

Frederick Hopkins was an American medical researcher who was born as the Civil 
War broke out in 1861. In 1900 he isolated an amino acid. (Other researchers had discov- 
ered two others before him but had not investigated their importance.) Hopkins called his 
amino acid tryptophan. From a review of other research, he found that farm animals could 
not be kept alive if their only sources of protein were things that included no tryptophan. No 
matter how much protein they got, animals seemed to require trace amounts of tryptophan 
to survive. 

By 1906 chemists had isolated at least 13 amino acids. Each was an essential building 
block of protein molecules. It occurred to Hopkins that these particular amino acids (which 
were commonly found in foods) were essential to life. Not for the protein and calories they 
provided; those could come from anywhere. There was something else these amino acids 
provided that was essential to life — even if only supplied in trace amounts. 

Hopkins reviewed Eijkman’ s work and discovered that it was an amino acid in brown 
rice feed that prevented beriberi. He found that it was not j ust fruit that prevented scurvy (as 
first discovered by Lind in 1747). It was a particular amino acid in fruit. 

Hopkins decided that diseases such as beriberi, scurvy, pellagra, and rickets were not 
caused by a thing (a germ) but by the absence (or deficiency) of something. Hopkins be- 
lieved that these diseases were caused by a dietary deficiency of amine groups of molecules 
(combinations of nitrogen and hydrogen atoms found in amino acids). He named this group 
of acids by combining the Latin word for life with “amines” and got vitamines. 

A few years later, researchers discovered that not all essential vitamins contained 
amines. They dropped the “e” to form the word vitamin — which we still use today. How- 
ever, research in nutrition has ever since been shaped by Hopkins’s discovery of vitamins. 


Apple, Rima. Vitamcinia: Vitamins in American Culture. New Brunswick, NJ: Rutgers 
University Press, 1996. 

Becker, Stanley. Butter Makes Them Grow: An Episode in the Discovery of Vitamins. 
Hartford: Connecticut Agricultural Experiment Station, 1997. 

Carpenter, Kenneth. Forgotten Mysteries in the Early History of Vitamin D. Washing- 
ton, DC: American Institute of Nutrition, 2005. 

Rucker, Robert. Handbook of Vitamins. New York: CRC Publishers, 2001. 

Yan, Kun. Stories of the Discovery of Vitamins: The Young Doctors Collection. 
Bloomington, IN: Authorhouse, 2005. 



Fun Facts: Think all sweets are bad for you? Hershey’s Sugar Free 
/ Chocolate Syrup has 10 percent vitamin E per serving. 


More to Explore 


Radioactive Dating 

Year of Discovery: 1907 


What Is It? The use of radioactive decaying elements to calculate the age 
of rocks. 

Who Discovered It? Bertram Boltwood 


Why Is This One of the 100 Greatest? 

Nothing is more basic than knowing your age — or the age of your house, or of a tree in 
your yard. For science, the same is true for Earth and for the rocks that make up Earth’s 
crust. 

Scientists had been estimating Earth’s age for thousands of years. However, these 
were little more than guesses. Boltwood discovered the first reliable way to calculate the 
age of a rock. Since some rocks are nearly as old as the earth, dating these rocks provided 
the first reasonable estimate of Earth’s age. 

Boltwood’ s discovery also allowed scientists to date individual rock layers and strata 
and to study the history of Earth’s crust. It led to aging techniques developed for plants, 
documents, societies, and ancient buildings. Boltwood gave back to geology a sense of time 
that the misestimates of previous researchers had taken away. 


How Was It Discovered? 

Radioactivity was discovered by Marie Curie at the end of the nineteenth century. In 
1902 Frederick Soddy (who later discovered isotopes) and Ernst Rutherford jointly discov- 
ered that uranium and thorium radioactively decayed at a constant rate. (It always takes ex- 
actly the same amount of time for exactly half of the radioactive atoms in a sample to decay. 
It’s called a half-life.) They also discovered that these two radioactive elements fissioned 
(radioactively decayed) into other elements in a fixed sequence — they always fissiioned in 
the same way into the same elements. The stage was set for someone to figure out how to 
use this new information. 

Bertram Boltwood was born in 1870 in Amherst, Massachusetts. He studied physics 
(and later taught physics) at Yale University. While doing research in 1905, Boltwood no- 
ticed that when he analyzed the composition of minerals containing uranium or thorium, he 
always found lead. 

Thinking that this find might be significant, he studied 43 mineral samples and ranked 
them by their estimated age. The amount of lead in these samples always increased as the 
samples grew older, just as the amount of uranium in them decreased. Boltwood concluded 

119 



120 Radioactive Dating 


that the radioactive decay series starting with uranium ended by creating lead — which was 
not radioactive. (Uranium eventually decayed into lead.) He studied the same process with 
thorium minerals and found the same result. 

Boltwood surmised that, if uranium and thorium decayed at fixed, known rates, then 
he should be able to use the amount of lead and the amount of either of these radioactive ma- 
terials in a rock sample to determine how old the rock is — that is, how long it had been since 
the radioactive decay process in that rock began. In his test samples, he used a Geiger coun- 
ter to estimate how many atoms of uranium decayed per minute and an early mass spec- 
trometer to determine how much of each trace element existed in the rock sample. 

Knowing how much lead and uranium currently existed in the sample, knowing how 
fast the uranium decayed, and knowing the half-life of that particular uranium isotope, 
Boltwood could then calculate how long radioactive decay had been occurring in that rock. 
This would tell him how old the rock was. 

In 1907 Boltwood published his calculations for the ages of 10 mineral samples. In ev- 
ery case they were startlingly old, showing that these rock samples (and the earth) were 
tens — and even hundreds — of times older than previously thought. Boltwood estimated the 
age of Earth at over 2.2 billion years (low based on present knowledge, but well over 10 
times older than any previous estimate). 

In 1947 American chemist Willard Libby realized that the recently discovered carbon 
isotope, carbon- 14, could be used to date plant and animal remains in the same way that ura- 
nium was used to date rocks. Libby’s carbon-14 dating accurately dated plant tissue back to 
45,000 years and has been used to date paper samples as well as plant tissue. 

Fun Facts: Radiometric dating can be performed on samples as small as 
a billionth of a gram. The uranium-lead radiometric dating scheme is one 
H of the oldest available, as well as one of the most highly respected. It has 
been refined to the point that any error in dates of rocks about three bil- 
lion years old is no more than two million years. The measurement is 
99.9 percent accurate. 

More to Explore 

Badash, Lawrence, ed. Rutherford and Boltwood: Letters on Radioactivity. New Ha- 
ven, CT: Yale University Press, 1999. 

Dickin, Alan. Radiogenic Isotope Geology. New York: Cambridge University Press, 
2005. 

Glut, Donald. Carbon Dates. Jefferson, NC: McLarland & Co., 1999. 

Liptak, Karen. Dating Dinosaurs and Other Old Things. New York: Lerner Publishing 
Group, 1998. 

Roth, Etinne. Nuclear Methods of Dating. New York: Springer-Verlag, 1997. 


Function of Chromosomes 


Year of Discovery: 1909 


What Is It? Genes are grouped (linked) in groups that are strung along 
chromosomes. 

Who Discovered It? T. H. Morgan 


Why Is This One of the 100 Greatest? 

Morgan’s discovery that genes were linked into groups and strung along chromosomes 
was the second major step in peeling back the mystery of heredity and evolution. Morgan’s 
discovery formed much of the foundation for later discoveries of how genes and chromo- 
somes do their work as well as the structure of the DNA molecule. 

Mendel established that traits (called “genes”) are passed from parents into the next 
generation. Darwin established the concepts that dictated evolution of species. Still, science 
had no idea how species evolved or how individual genes were passed to new generations. 

Studying a species of fruit flies, Professor T. H. Morgan at Columbia University both 
proved that Mendel’s theory was correct and established the existence of chromosomes as 
the carriers for genes. 


How Was It Discovered? 

By 1910, 44-year-old professor T. H. Morgan was the head of the biology department 
at New York’s Columbia University. All his energy, however, he saved for his research. 
Morgan refused to accept Mendel’s theories on heredity. Morgan didn’t believe in the exis- 
tence of genes since no one had physically seen a gene. 

Neither did he accept Darwin’s concept of survival of the fittest as the driving force of 
evolution. Morgan believed that evolution came from random mutations that slowly 
worked their way into and through a population. Morgan created “The Fly Room” to prove 
his ideas. 

Morgan’s Fly Room laboratory was a small, messy room with the overpowering reek 
of rotting bananas. Two walls were lined floor to ceiling with rows of corked glass bottles 
containing tens of thousands of tiny fruit flies. Their constant buzz was difficult to talk over. 

He chose to study fruit flies for four reasons. First, they were small (only 14-inch long). 
Second, they lived their entire lives on nothing but mashed banana. Third, they created a 
new generation in less than two weeks. Morgan could study almost 30 generations a year. 
Finally, they had few genes and so were much easier to study than more complex species. 


121 



122 Function of Chromosomes 


Morgan searched and waited for a random physical mutation (like eye color) to appear 
in one of the thousands of fruit flies born each month. He would then carefully track that 
mutation through subsequent generations to see if spread across the population and proved 
his theory. It was a mind-numbing effort for Morgan and his assistants. Each month, many 
thousands of new fruit flies had to be carefully examined under the microscope for 
mutations. 

In September 1910 Morgan found a mutation — a male fruit fly with clear white eyes 
instead of the normal deep red. The white-eyed male was carefully segregated in his own 
bottle and mated with a normal red-eyed female. 

If the eyes of these hatchlings were white, off-white, or even rose colored (as Morgan 
believed they would be), this random mutation — that provided no real Darwinian survival 
benefit or advantage — would have evolved (permanently changed) the species and Mor- 
gan’s theory of evolution by mutation would have been confirmed. 

It took three days to examine the 1 ,237 new flies. Every one had normal red eyes. Mor- 
gan was crushed. The mutation had disappeared. It hadn’t changed the species at all. Mor- 
gan was wrong. 

By October 20 the grandchildren of the original white-eyed male were hatched. 
One-quarter of this generation had white eyes; three-quarters had normal red eyes. 3 to 1: 
That was Mendel’s ratio for the interaction of a dominant and a recessive characteristic. 
T. H. Morgan’s own experiment had just proved himself wrong and Mendel’s gene theory 
right ! 

Additional mutations occurred frequently over the next two years. By studying these 
mutations and their effect on many generations of descendents, Morgan and his assistants 
realized that many of the inherited genes were always grouped together. (They called it 
“linked.”) 

By 1912 the team was able to establish that fruit fly genes were linked into four groups. 
Knowing that fruit flies had four chromosomes, Morgan suspected that genes must be 
strung along, and carried by, chromosomes. After 18 months of additional research, Mor- 
gan was able to prove this new theory. Chromosomes carried genes, and genes were strung 
in fixed-order lines (like beads) along chromosomes. 

While attempting to disprove Mendel’s work, Morgan both confirmed that Mendel 
was right and discovered the function of chromosomes and the relationship between chro- 
mosomes and genes. 

(f~^\ Fun Facts: Fruit flies can lay up to 500 eggs at a time, and their entire 
\T / lifecycle is complete in about a week. 

More to Explore 

Aaseng, Nathan. Genetics: Unlocking the Secrets of Life. Minneapolis, MN: Oliver 
Press, 1996. 

Allen, Garland. Thomas Hunt Morgan: The Man and His Science. Princeton, NJ: 
Princeton University Press, 1996. 

Edey, Maitland, and Donald Johanson. BLUEPRINTS: Solving the Mystery of Evolu- 
tion. New York: Penguin Books, 1994. 


More to Explore 123 


Riley, Herbert. Thomas Hunt Morgan. Frankfurt: Kentucky Academy of Sciences, 
1994. 

Sherrow, Victoria. Great Scientists. New York: Facts on File, 1998. 

Shine, Ian. Thomas Hunt Morgan, Pioneer of Genetics. Frankfurt: University Press of 
Kentucky, 1996. 

Sturtevant, A. H. A History of Genetics. Cold Spring Harbor, NY: Cold Spring Harbor 
Laboratory Press, 2001. 


Antibiotics 


Year of Discovery: 1910 


What Is It? Chemical substances that kill infectious microscopic organisms 
without harming the human host. 

Who Discovered It? Paul Ehrlich 


Why Is This One of the 100 Greatest? 

The word “antibiotic” comes from the Greek words meaning “against life.” Early folk 
medicine relied on some natural compounds that cured certain diseases — the ground bark of 
a tree, certain cheese molds, certain fungi. Doctors knew that these natural compounds 
worked, but had no idea of how or why they worked. 

Paul Ehrlich conducted the first modern chemical investigation of antibiotics and dis- 
covered the first antibiotic chemical compounds. His work opened a new era for medical 
and pharmacological research and founded the field of chemotherapy. Antibiotics (penicil- 
lin, discovered in 1928, is the most famous) have saved many millions of lives and trace 
their modem origin to Paul Ehrlich’s work. 


How Was It Discovered? 

Paul Ehrlich was born in Germany in 1854. A gifted student, he entered graduate 
school to study for a medical degree. There he became deeply involved in the process of 
staining microscopic tissue samples so that they would show up better under the micro- 
scope. The problem was that most dyes destroyed the tissue samples before they could be 
viewed. Ehrlich struggled to find new dyes that wouldn’t harm or kill delicate microscopic 
organisms. This work showed Ehrlich that some chemical compounds killed some types of 
tissue and made him wonder if the process could be controlled. 

By 1885 it had become clear that the causative agent for many illnesses was microor- 
ganisms. Many scientists made a great effort to study these bacteria under the microscope. 
Again Ehrlich found that many of the available dyes and stains killed the organisms before 
they could be studied. This finding inspired Ehrlich to propose that chemical compounds 
may exist that could kill these organisms without harming the human patient, thus curing an 
illness by killing only its causative agent. 

In the mid- 1 890s, Ehrlich shifted his focus to studies of the immune system and how to 
control the reaction between chemical toxins and antitoxins. Again it occurred to Ehrlich 
that, just as antitoxins specifically sought a toxin molecule to which they were related and 
destroyed it, so, too, he might be able to create a chemical substance that would go straight 

124 



More to Explore 125 


to some disease-causing organism and destroy it. Ehrlich called such a chemical substance a 
“magic bullet.” It seemed that 25 years of work had led him directly to this idea. 

During this same period, many specific disease-causing bacteria were being identified 
and studied. This gave Ehrlich well-understood targets to attack as he sought ways to create 
magic bullets. He chose to start with spirochaete, the microorganism that caused syphilis. 
Ehrlich began testing different chemicals using an arsenic base for his compounds. Arsenic 
had been effective in destroying a number of other microorganisms. 

By 1907, Ehrlich had reached the 606th compound to be tested. He tested this com- 
pound on rabbits infected with syphilis. It cured the rabbits. Ehrlich named it salvarsan and 
conducted over 100 additional tests to be sure it worked and that it wouldn’t harm human 
patients. He then worked for two more years to develop a form of this drug that was easier to 
manufacture and that was easier to administer. Of the thousand variations he tried, version 
number 914 was the best. He named it neosalvarsan. 

Ehrlich’ s final test of neosalvarsan was to give it to terminal patients suffering from the 
dementia that was the final stage of syphilis. While neosalvarsan helped all of these pa- 
tients, remarkably, several completely recovered. 

Neosalvarsan was the first man-made chemical that would specifically destroy a 
target organism and not affect the human patient. This discovery founded the field of 
chemotherapy. 

/f~f Fun Facts: Resistance to antibiotics works by the ordinary rules of natu- 
'jJ ral selection: that segment of the bacteria population that has a natural 
® ability to counter the drug’s effect will survive, so that their genes even- 
tually are shared by the entire population. Many disease-causing viruses 
and bacteria have developed virtual immunity to many antibiotics, mak- 
ing medical planners fear massive disease outbreaks in the near future. 

More to Explore 

Asimov, Isaac. Asimov’s Chronology of Science and Discovery. New York: Harper & 
Row, 1989. 

Baumier, Ernest. Paul Ehrlich: Scientist for Life. Teaneck, NJ: Holmes & Meier, 
1994. 

Dyson, James. A History of Great Inventions. New York: Carroll & Graf Publishers, 
2001 . 

Ehrlich, Paul. Studies in Immunity. New York: John Wiley & Sons, 1990. 

Pickstone, John, ed. Medical Innovations in Historical Perspective. New York: 
Palgrave Macmillan, 1993. 

Zannos, Susan. Paul Ehrlich and Modern Drug Development . Hockessin, DE: Mitch- 
ell Lane, 2002. 


Fault Lines 


Year of Discovery: 1911 


What Is It? Earthquakes happen both along, and because of, fault lines in the 
earth’s crust. 

Who Discovered It? Harry Reid 


Why Is This One of the 100 Greatest? 

Scientists now know that they can predict the locations of future earthquakes by map- 
ping the locations of fault lines. However, just a century ago this simple truth was not 
known. 

Harry Reid’ s discovery that earthquakes happen along existing fault lines provided the 
first understanding of the source and process of earthquakes. This discovery laid the foun- 
dation for the discovery of Earth’s crustal plates and plate tectonics in the late 1950s. 

Reid’s discovery was called a major breakthrough in earth science and provided the 
first basic understanding of Earth’s internal processes and of how rocks behave under 
stress. 


How Was It Discovered? 

By 1750, scientists knew that there were fault lines (like long cracks) snaking through 
Earth’s upper crust where two dissimilar kinds of rocks came together. By 1900, scientists 
knew that these fault lines were associated with earthquakes. 

The mistake scientists made, however, was to agree that earthquakes caused the fault 
lines. It was as though the crust had been a smooth block of rock that had been cracked by an 
earthquake, with one side sliding past the other to create the rock mismatch. Earthquakes 
happened, and fault lines were the telltale residues of past earthquakes. 

Harry Fielding Reid was born in Baltimore in 1859. When he received his early 
schooling in Switzerland, these ideas were what were taught in geology classes. They were 
what Reid learned. However, earthquakes and fault lines were of little interest to Reid. Liv- 
ing in Switzerland focused his primary interest on mountains and glaciers. 

Reid returned to Baltimore to attend college at Johns Hopkins University in 1865 (at 
the age of 16). He stayed long enough to receive a doctorate in geology in 1885. Beginning 
in 1889, Reid took positions as a university professor with a research emphasis on glaciers. 

Reid traveled extensively through Alaska and the Swiss Alps mapping and studying 
glaciers, their movement, their formation, and their effects on the landscape. He wrote arti- 
cles and papers on glacial structure and movement. 

126 



More to Explore 127 


In April 1906 the great San Francisco earthquake struck and most of the city either top- 
pled or was burned. In late 1906 the state of California formed the California State Earth- 
quake Investigation Commission to study the San Francisco earthquake and to determine 
the risk to the state of possible future earthquakes. Reid was asked to serve as a member of 
this nine-member commission. 

This commission study turned Reid’s interest toward earthquakes and fault lines. He 
mapped and studied the San Andreas fault line and roamed the central California coastal re- 
gion mapping other fault lines. Always he searched for an answer to the question: What 
caused earthquakes? 

Reid carefully studied the rocks along California fault lines and concluded that they 
suffered from long-term physical stress, not just from the jolt of a sudden earthquake. Reid 
saw that great stresses must have existed in the rocks along the San Andreas fault line for 
centuries — even for millennia — before the earthquake happened. 

That meant that the fault lines had to have existed ///'*,? and stress along them caused the 
earthquake. Stress built up and built up in the rocks until they snapped. That “snap” was an 
earthquake. 

Reid developed the image of the rock layers along fault lines acting like rubber bands. 
Stresses deep in the earth along these fault lines pulled the rocks in different directions, 
causing these rocks to stretch — like elastic. Once the stress reached the breaking point, the 
rocks elastically snapped back — causing an earthquake. 

Fault lines caused earthquakes, not the other way around. That meant that studying 
fault lines was a way to predict earthquakes, not merely study their aftermath. Reid had dis- 
covered the significance of the earth’s spider web maze of fault lines. 

Fun Facts: The destructive San Francisco earthquake of 1906 horizon- 
\T/ tally shifted land surfaces on either side of the San Andreas fault up to 2 1 
• ft (6.4 m). 


More to Explore 

Branley, Franklyn. Earthquakes. New York: HarperTrophy, 1998. 

Harrison, James. Discover Amazing Earth. New York: Sterling Publishing Co., 2005. 
Sherrow, Victoria. Great Scientists. New York: Facts on File, 1998. 

Thomas, Gordon. The San Francisco Earthquake. New York: Day Books, 1996. 
Ulin, David. The Myth of Solid Ground. New York: Penguin, 2005. 


Superconductivity 


Year of Discovery: 1911 


What Is It? Some materials lose all resistance to electrical current at super-low 
temperatures. 

Who Discovered It? Heike Kamerlingh Onnes 


Why Is This One of the 100 Greatest? 

Superconductivity is the flow of electrical current without any resistance to that flow. 
Even the best conductors have some resistance to electrical current. But superconductors do 
not. Unfortunately, superconductors only exist in the extreme cold of near absolute zero. 

Even though the practical application of this discovery has not yet been realized, su- 
perconductivity holds the promise of super-efficient electrical and magnetic motors, of 
electrical current flowing thousands of miles with no loss of power, and of meeting the 
dream of cheap and efficient electricity for everyone. Superconductivity will likely spawn 
whole new industries and ways of generating, processing, and moving electrical energy. 
But that potential still lies in the future. 


How Was It Discovered? 

Heike Onnes was born in 1853 in Groningen, the Netherlands, into a wealthy family 
that owned a brick making factory. As he went through college and graduate school, he 
drew considerable attention for his talent at solving scientific problems. By the time he was 
18, Onnes had become a firm believer in the value of physical experimentations and tended 
to discount theories that could not be demonstrated by physical experiment. 

At the age of 25, Onnes focused his university research on the properties of materials at 
temperatures approaching the coldest possible temperature (-456°F or -269°C). The exis- 
tence of that temperature, the temperature at which all heat energy is gone and all motion 
— even inside an atom — ceases, was discovered by Lord Kelvin, and is called 0° Kelvin 
(0°K) or absolute zero. 

Several theories existed about what happened near 0°K. Lord Kelvin believed that ab- 
solute zero would stop the motion of electrons. Electrical current would cease and resis- 
tance to that current would be infinitely large. Others believed the opposite — that resistance 
would fall to zero and electrical currents would flow forever. 

Everyone had a theory. Onnes decided to find out, to test the theories. 


128 



How Was It Discovered? 129 


However, there was a problem. No method existed to cool anything anywhere near 
-269°C. Luckily, Onnes was the physics department chair at the University of Leyden, and 
that department came equipped with a well-funded physics lab that Onnes could use. 

In 1907 Onnes invented thermometers that could measure temperatures as extreme as 
absolute zero. In 1908 he discovered a way to cool the gas helium so cold that it turned into a 
liquid. He was able to continue to chill the super-cold liquid until, late that year, he chilled 
liquid helium to 0.9°K — less than one degree above absolute zero! Onnes realized that he 
could use this liquid helium to chill other materials to near 0°K to measure their electrical 
resistance. 

By 1911 Onnes had developed canisters capable of holding and storing his super-cold 
liquid helium and had set up a small production line. He began his electrical studies by chill- 
ing first platinum and then gold to near absolute zero. However, the electrical currents he 
measured were erratic, his results inconclusive. 

Onnes decided to switch to liquid mercury. He filled a U-shaped tube with mercury 
and attached wires to each end of the U. The wires were attached to a meter to measure elec- 
trical resistance. He used liquid helium at 0.9°K to cool the mercury. 

As the temperature dipped below 40°K (-229°C) electrical resistance began to drop. It 
dropped steadily as the temperature dipped below 20°K. And then, at 4. 19°K resistance 
abruptly disappeared. It fell to zero. 

Onnes repeated the experiment many times over the next few months and always got 
the same result. Below 4. 19°K, there was no resistance to the flow of electricity. An electric 
current would flow unimpeded for ever! He called it superconductivity. 

Onnes had discovered superconductivity, but he could not theoretically explain it. He 
only suspected that it had something to do with the (then) recently discovered Quantum 
Theory. It was not until 1951 that John Bardeen developed a mathematical theory to explain 
superconductivity. 

A search began to find ways to create superconductivity at higher (more practically 
reached) temperatures. The current record (using — unfortunately — toxic ceramic com- 
pounds made with mercury and copper) is 138°K (-131°C). Once a way is found to create 
superconductivity at warmer temperatures, the value of Onnes’s discovery will be 
unlimited. 



Fun Facts: AT CERN, the European high-energy physics research lab, 
scientists used a one-time jolt of electricity to start an electrical current 
flowing through a superconductor circuit. That electrical current 
ran — with no additional voltage input — for five years with no loss of 
power. In common house wires, an electrical current would stop within a 
few milliseconds once the voltage is removed because of the resistance 
of electrical wires. 


130 Superconductivity 


More to Explore 

Ford, P. J. The Rise of Superconductors. New York: CRC Press, 2005. 

Gale Reference. Biography: Heike Kamerlingh Onnes. New York: Gale Research, 
2004. 

Lampton, Christopher. Superconductors. Berkeley Heights, NJ: Enslow, 1997. 

Matricon, Jean. The Cold Wars: A History of Superconductivity. New Brunswick, NJ: 
Rutgers University Press, 2003. 

Shachtman, T. Absolute Zero and the Conquest of Cold. New York: Houghton Mifflin, 
1999. 


Atomic Bonding 

Year of Discovery: 1913 


What Is It? The first working theory of how electrons gain, lose, and hold en- 
ergy and how they orbit the nucleus of an atom. 

Who Discovered It? Niels Bohr 


Why Is This One of the 100 Greatest? 

Marie Curie opened the century by proving that there was a subatomic world. Einstein, 
Dirac, Heisenberg, Born, Rutherford, and others provided the new theoretical descriptions 
of this subatomic world. But proving what lurked within an atom’s shell, and what gov- 
erned its behavior, lingered as the great physics challenges of the early twentieth century. 

It was Niels Bohr who discovered the first concrete model of the electrons surrounding 
an atom’s nucleus — their placement, motion, radiation patterns, and energy transfers. 
Bohr’s theory solved a number of inconsistencies and flaws that had existed in previous at- 
tempts to guess at the structure and activity of electrons. He combined direct experiment 
with advanced theory to create an understanding of electrons. It was an essential step in 
science’s march into the nuclear age. 

How Was It Discovered? 

Niels Bohr was only 26 in 1912 — very young to step into the middle of a heated phys- 
ics controversy. But that spring, as a new physics professor at the University of Copenha- 
gen, Bohr realized atomic theory no longer matched the growing body of experimental 
atomic data. One of Bohr’s experiments showed that classical theories predicted that an or- 
biting electron would continuously lose energy and slowly spiral into the nucleus. The atom 
would collapse and implode. But that didn’t happen. Atoms were amazingly stable. Some- 
thing was wrong with the existing theories — and Bohr said so. 

There was no way to actually see an atom, no way to peer inside and directly observe 
what was going on. Scientists had to grope in the dark for their theories, sifting through in- 
direct clues for shreds of insight into the bizarre workings of atoms. 

Atomic experimenters were building mountains of data. They recorded the particles 
created from atomic collisions. They measured the angles at which these new particles 
raced away from the collision site. They measured electrical energy levels. But few of these 
data fit with atomic theories. 


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132 Atomic Bonding 


As Bohr began to organize his teaching in 1913, he read about two new experimental 
studies. First, Enrico Fermi found that atoms always emitted energy in the same few 
amounts (or bursts) of energy. Fie called these bursts discrete quanta (quantities) of energy. 

Second, chemists had studied the amount of energy that each element’ s atoms radi- 
ated. They found that if they passed this radiation through a prism, the radiation was not 
continuous over the whole frequency spectrum, but came in sharp spikes at certain discrete 
frequencies. Different elements showed different characteristic patterns in these energy 
spikes. Neither study fit with existing theories. 

Bohr studied and compared these different, and apparently unrelated, bits of data, 
knowing that the new data had to relate somehow — since they dealt with characteristics and 
emissions from the same source: atoms. 

Bohr sifted and resifted the data and the theories over an eight-month period, searching 
for a way to make the experimental data fit with some atomic theory. By late that year he 
had discovered a revolutionary idea: Electrons must not be as free to roam as previously 
thought. 

He theorized that the electrons circling an atom’s nucleus could only exist in certain, 
discrete, fixed orbits. In order to jump to a closer orbit, an electron would have to give off a 
fixed amount of energy (the observed spikes and quanta of radiated energy). If an electron 
were to jump into a higher orbit, it would have to absorb a fixed quanta of energy. Electrons 
couldn’t go wherever they wanted or carry any amount of energy. Electrons must be in one 
or another of these few specific orbits. Electrons must gain and lose energy in specific 
quanta. 

Bohr’ s atomic model was a revolutionary idea and a complete departure from previous 
ideas. However, it fit well with experimental observations and explained all of the inconsis- 
tencies of previous theories. This model also explained how and why chemical elements 
bonded with each other as they did. 

Bohr’s discovery received instant acclaim and acceptance. For 50 years it served as the 
accepted model of an atom and of the motion of electrons within the atom. 


Aserud, Finn. Redirecting Science: Niels Bohr and the Rise of Nuclear Physics. Lon- 
don: Cambridge University Press, 1990. 

Blaedel, Niels. Harmony and Unity: The Life of Niels Bohr. Chicago: Science Tech- 
nology Publishing, 1988. 

Moore, Ruth. Niels Bohr: The Man, His Science, and the World They Changed. Cam- 
bridge, MA: MIT Press, 1985. 

Murdoch, D. R. Niels Bohr’s Philosophy of Physics. London: Cambridge University 
Press, 1999. 

Rozental, S. Niels Bohr: His Life and Work. New York: John Wiley & Sons, 1997. 



Ti Fun Facts: Niels Bohr worked at the secret Los Alamos laboratory in 
J New Mexico, on the Manhattan Project (the code name for the effort to 
' develop atomic bombs for the United States during World War II). 


More to Explore 


Year of Discovery: 1913 


Isotopes 


What Is It? Isotopes are different forms of the same chemical element that 
have identical physical and chemical properties but different atomic 
weights. 

Who Discovered It? Frederick Soddy 


Why Is This One of the 100 Greatest? 

Isotopes of an element are slightly different forms of that element. Isotopes have the 
same chemical, physical, and electrical properties as the original element, but have a differ- 
ent number of neutrons in their nucleus. The discovery of isotopes created a new dimension 
and concept for physics and chemistry. 

This discovery answered baffling problems that had stymied physics researchers 
studying radioactive elements. The study of isotopes became a key foundation for the de- 
velopment of atomic power and weapons. Isotopes are also critical to geology since carbon 
dating and other rock-dating techniques all depend on the ratios of specific isotopes. 

This one discovery removed roadblocks to scientific progress, opened new fields of 
physics and chemistry research, and provided essential research tools to earth science re- 
search. 


How Was It Discovered? 

Frederick Soddy was bom in 1877 in Sussex, England. In 1910 Soddy accepted a posi- 
tion at the University of Glasgow as a lecturer in radioactivity and chemistry. 

The study of radioactive elements was still exciting and new. Radioactive elements 
were identified by differences in their mass, atomic charge, and radioactive properties, in- 
cluding the kinds and energies of different particles they emitted. 

However, using this system, scientists had already identified 40 to 50 radioactive ele- 
ments. But there existed only 10 to 12 places for all of these radioactive elements on the peri- 
odic chart of elements. Either Mendeleyev’s periodic chart was wrong or — for some 
unknown reason — radioactive elements fell outside the logic and order of the periodic chart. 

Neither answer made any sense, and radioactive research ground to a halt. 

Soddy decided to study the three known subatomic particles emitted by the various ra- 
dioactive elements (alpha, beta, and gamma particles). Soddy found that alpha particle held 
a positive charge of two (as would two protons) and a mass equal to four protons. Gamma 


133 



134 Isotopes 


rays had neither charge nor mass, only energy, so they didn’t affect the nature of the atom at 


Beta particles had no measurable mass but held a negative charge of one. They were 
apparently just electrons. 

When an atom emitted a beta particle, it lost a negative charge. Soddy realized that was 
the same as gaining a positive charge. Emit an alpha particle and lose two positive charges 
from the nucleus. Emit a beta particle and gain one. 

Because the periodic table was organized by the number of protons in the nucleus of an 
atom — from the lightest element (hydrogen) up to the heaviest known element (uranium), 
Soddy realized that the emission of an alpha particle would, in effect, shift the atom two 
spaces to the left on the periodic chart and the emission of a beta particle shifted it one place 
to the right. 

It must be, he concluded, that atoms of many elements could exist in several different 
spaces on the periodic chart. Soddy used new spectrographic research techniques (discov- 
ered by Gustav Kirchhoff and Robert Bunsen in 1859) to show that — even though they had 
a different atomic mass and so occupied different spaces on the periodic chart — atoms of 
uranium and thorium were still the same, original element. 

This meant that more than one element could occupy the same spot on the periodic 
chart and that atoms of one element could occupy more than one spot and still be the same, 
original element. Soddy named the versions of an element that occupied spots on the peri- 
odic chart — other than that element’s “normal” spot — isotopes, from the Greek words 
meaning “same place.” 

Later that same year (1913), American chemist Theodore Richards measured the 
atomic weights of lead isotopes resulting from the radioactive decay of uranium and of tho- 
rium and proved Soddy’ s theory to be true. 

However, Soddy ’s explanation of his discovery was not completely accurate. 
Chadwick’s discovery of the neutron (in 1932) was needed to correct Soddy’s errors and to 
complete the understanding of Soddy’s concept of isotopes. 

Soddy had tried to explain his isotopes using only protons and electrons. Chadwick 
discovered that as many neutrally charged neutrons existed in the nucleus as did positively 
charged protons. Gaining or losing neutrons didn’t change the electric charge of or the 
properties of the element (since elements were defined by the number of protons in the nu- 
cleus). It did, however, change the atomic mass of the atom and so created an isotope of that 
element. 

Soddy discovered the concept of isotopes. But an understanding of neutrons was 
needed in order to fully understand them. 


all. 



Fun Facts: Isotopes are more important than most people think. Every 
/ ancient rock, fossil, human remain, or plant ever dated was dated using 
i isotopes of various elements. Natural radioactivity is created by isotopes. 
The atomic bomb uses an isotope of uranium. 


More to Explore 135 


More to Explore 

Clayton, Donald. Handbook of Isotopes in the Cosmos. New York: Cambridge Uni- 
versity Press, 2003. 

James, Richard. Adventures of the Elements. Pittsburgh: Three Rivers Council, 1997. 

Kauffman, George. Frederick Soddy: Early Pioneer in Radiochemistry. New York: 
Springer, 2002. 

Merricks, Linda. The World Made New: Frederick Soddy, Science, and Environment. 
New York: Oxford University Press, 1996. 

Rattanski, P. M. Pioneers of Science and Discovery. Charleston, WV: Main Line 
Books, 1997. 


Earth’s Core and Mantle 


Year of Discovery: 1914 


What Is It? The earth is made up of layers, each of a different density, temper- 
ature, and composition. 

Who Discovered It? Beno Gutenberg 


Why Is This One of the 100 Greatest? 

It is impossible to see, to venture, or even to send probes more than a few miles under 
the surface of Earth. Almost all of the 4,000+ miles from the surface to the center is un- 
reachable to humans. Yet scientists could not begin to understand our planet and its forma- 
tion without having an accurate knowledge of that interior. 

Beno Gutenberg provided the first reasonable accounting of Earth’s interior. His dis- 
covery proved that Earth wasn’t a solid homogeneous planet, but was divided into layers. 
Gutenberg was the first to correctly estimate the temperature and physical properties of 
Earth’s core. His discoveries have been so important that he is often considered the father of 
geophysics. 


How Was It Discovered? 

Born in 1889 in Darmstadt, Germany, Beno Gutenberg loved science as a boy and al- 
ways knew he’d be a meteorologist. As he began his second year of university meteorologi- 
cal study in 1907, he saw a notice announcing the formation of a department of the new 
science of geophysics (Earth physics) at the University of Gottingen. 

The idea of a whole new science fascinated Gutenberg. He transferred to Gottingen 
and, while holding onto a major in meteorology, studied under Emil Wiechert, a pioneer in 
the emerging science of seismology — the study of seismic waves caused by earthquakes 
and earth tremors. 

By the time of his graduation in 1913, Gutenberg had shifted from meteorology (study 
of the atmosphere) to geophysics (study of Earth’s interior). It was a case of being in the 
right place at the right time. Gutenberg had access to all of Wiechert’ s data and studies, the 
most extensive and comprehensive collection of seismic data in the world. Wiechert had fo- 
cused on collecting the data. Gutenberg focused on studying the patterns of those data. 

Gutenberg found that, typically, seismic waves did not reach all parts of the earth’s 
surface, even when the tremor was strong enough to have been detected everywhere. There 
always existed a shadow zone more or less straight across the globe from an event where no 
seismic waves were ever detectable. 


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More to Explore 137 


He also noticed that seismic waves seemed to travel at different speeds on different tra- 
jectories through the earth. This all made Gutenberg suspect that the interior of the earth 
was not a solid, homogeneous mass. It must have several separate layers or regions. 

Gutenberg settled on the image of the earth as an egg. The surface of the earth was thin 
and brittle like an eggshell. He realized that there must be a core to Earth (like an egg yoke) 
that was more dense than the surrounding mantle (the egg white). 

If this image held true, seismic waves approaching the core would change speeds and 
be diffracted (bent) because of the density difference between layers. One of the kinds of 
seismic waves that Gutenberg studied was transverse waves. These waves would not enter 
the core at all. Knowing that transverse waves dissipate quickly in the liquid ocean, 
Gutenberg surmised that Earth’s core also had to be liquid. 

Gutenberg had enough data from the recorded diffractions of enough seismic waves to 
calculate how big the core had to be and what its density had to be in order to create the dif- 
fraction patterns seismologists recorded. The core of the earth, he said, had a radius of 2,100 
miles. 

Based on these calculations, on chemical experiments he ran in early 1914, and on the 
measured chemical composition of meteorites, Gutenberg estimated that the core was a liq- 
uid mixture of nickel and iron, while the mantel was made up of rock material. 

Gutenberg’s model was quickly accepted and was not improved upon until 1938. In 
that year, Inge Lehman completed a detailed study of “P” waves (another kind of seismic 
wave) with vastly improved equipment from that used in 1914. Her research showed that 
Earth’s core was divided into a solid inner core and a surrounding liquid outer core. She also 
broke the mantle into an inner and an outer mantle. This discovery completed our basic im- 
age of Earth’s interior. 


Crossley, D. Earth’s Deep Interior. Abingdon, England: Taylor & Francis, 1997. 

Gibbons, Gail. Planet Earth: Inside Out. New York: HarperCollins, 1998. 

Gutenberg, Beno. Seismicity of the Earth and Associated Phenomena. New York: 
Textbook Publishers, 2003. 

Jacobs, John. Earth’s Core. Chevy Chase, MD: Elsevier Science Books, 1997. 
Manzanero, Paula, ed. Scholastic Atlas of Earth. New York: Scholastic, 2005. 

Vogt, Gregory. Earth’s Core and Asthenosphere. New York: Lemer Group, 2004. 



V Fun Facts: The crust of the earth is solid. So is the inner core. But in be- 
/ tween, the outer core and mantle (90 percent of the mass of the earth) are 
' liquid to molten semi-solid. We do not live on a particularly solid planet. 


More to Explore 


Continental Drift 

Year of Discovery: 1915 


What Is It? Earth’s continents drift and move over time. 
Who Discovered It? Alfred Wegener 


Why Is This One of the 100 Greatest? 

Before Wegener’s discovery, scientists thought that the earth was a static body — never 
changing, now as it always has been. Alfred Wegener’s discovery that Earth’s continents 
drift across the face of the planet led to modem tectonic plate theories and to a true under- 
standing of how Earth’s crust, mantel, and core move, flow, and interact. It created the first 
sense of Earth’s dynamic history. 

Wegener’s discovery solved nagging mysteries in a dozen fields of study — and stirred 
up new questions still being debated today. This discovery stands as a cornerstone of our 
modem understanding of earth sciences. 


How Was It Discovered? 

Albert Wegener was born in 1880 in Berlin. Always restless and more of a doer than a 
thinker , he switched his college major from astronomy to meteorology because “astronomy 
offered no opportunity for physical activity.” Upon graduation, Wegener signed on for me- 
teorological expeditions to Iceland and Greenland in 1906 and 1908. 

While on tour in 1910, Wegener noticed the remarkable fit of the coastlines of South 
America and Africa. He was not the first scientist to notice this fit, but one of the first to 
think that it was important. 

In 191 1, new ocean maps showed the Atlantic Ocean continental shelves. (Continental 
shelves are shallow, underwater shelves extending out from continents.) Wegener noticed 
an even better fit between the continental shelves of South America and Africa. They “fit 
like pieces of a jigsaw puzzle.” 

Wegener knew that this perfect fit couldn’t be just a coincidence and suspected that 
those two continents were once connected — even though they were now separated by sev- 
eral thousand miles of ocean. This was a radical notion since all scientists assumed that the 
continents never moved from their fixed positions on Earth. 

In that same year, Wegener read studies that noted the same fossil finds in South 
America and in corresponding parts of coastal Africa. Many scientists proposed that there 
once existed a land bridge between the two so that plant and animal species could intermix. 
This bridge, they assumed, long ago sank to the bottom of the sea. 

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More to Explore 139 


Wegener believed a land bridge was impossible. It would have left telltale signs on the 
ocean floor and would create gravitational anomalies that did not exist. In 1912, he decided 
to build a body of evidence from a variety of fields to prove that the continents had once 
been joined. 

He used the extensive fieldwork of Eduard Suess to provide most of his geological 
data. Suess discovered that, in place after place, rocks on coasts that faced each other across 
the oceans often matched exactly. 

Wegener poured through the findings of hundreds of geologic surveys to show that the 
rock formations, mix of rock kinds, and rock stratification on the two continents (South 
America and Africa) matched up and down the coastline. He found formations known as 
pipes (associated with diamonds) on both sides of the south Atlantic, exactly opposite each 
other. 

He also collected records of past and present plant communities on both sides of the 
Atlantic and mapped them to show how they matched up and down the coast. 

The only explanation Wegener could offer for these similarities was that South Amer- 
ica and Africa used to be joined as a single continent and one or both had since drifted off. 
He extended his theory to cover all continents (e.g., North America used to be joined with 
Europe) and arrived at the conclusion that, at one time, all of Earth’s land masses had been 
joined in a single massive continent that he named Pangaea (Greek for “all Earth”) 

Wegener published his discoveries and his theory in 1915. Scientists around the world 
were both skeptical of his conclusions and impressed by the amount of, and variety of, data 
he presented. Wegener had discovered continental drift, but stumbled when he couldn’t say 
how the continents drifted (what force drove them through the denser oceanic floor). Forty 
years later, Harvey Hess discovered sea floor spreading and filled this hole in Wegener’s 
theory. 


Cohen, Bernard. Revolutions in Science. Cambridge, MA: Harvard University Press, 


Hallam, Anthony. A Revolution in the Earth Sciences: From Continental Drift to Plate 
Tectonics. New York: Clarendon Press, 1993. 

LeGrand, H. Drifting Continents and Shifting Theories. New York: Cambridge Uni- 
versity Press, 1998. 

Oreskes, Naomi. The Rejection of Continental Drift: Theory and Method in American 
Earth Sciences. New York: Oxford University Press, 1999. 

Wegener, Alfred, and Kurt Wegener. The Origins of Continents and Oceans. New 
York: Dover, 1996. 



Fun Facts: The Himalayas, the world’s highest mountain system, are the re- 
sult of the ongoing collision of two huge tectonic plates (the Eurasia plate 
and the Indian subcontinent), which began about 40 million years ago. 


More to Explore 


1995. 


Black Holes 


Year of Discovery: 1916 


What Is It? A collapsed star that is so dense, and whose gravitational pull is so 
great, that not even light can escape it. Such stars would look like black 
holes in a black universe. 

Who Discovered It? Karl Schwarzschild 


Why Is This One of the 100 Greatest? 

Many consider black holes to be the ultimate wonder of the universe, the strangest of 
all stellar objects. Black holes might be the birthplace of new universes, even new dimen- 
sions. Black holes might mark the beginning and end of time. Some consider them to be 
possible time travel machines as well as a way to travel faster than the speed of light. Many 
believe that black holes could be the ultimate future energy source, providing power sta- 
tions throughout the galaxy. 

Certainly, black holes were first a theoretical, and then a practical, great mystery of as- 
tronomy in the twentieth century. Their discovery led science a giant step closer to under- 
standing the universe around us and provided a solid confirmation of Einstein’s theory of 
relativity. 


How Was It Discovered? 

A black hole is not really a hole at all. It is a collapsed star that crushed in on itself. As 
the star condenses, its gravity increases. If the collapsed star’s gravity becomes so strong 
that not even light (particles traveling at light speed) can escape the gravitational pull, then 
it will appear like a black hole (in the pitch black background of space). 

Two men get the credit for the discovery of these bizarre and unseeable phenomena. The 
first was German astronomer wonder-boy, Karl Schwarzschild. As a child, Schwarzschild 
was fascinated by celestial mechanics (the motion of the stars), and he published his first two 
papers on the theory of how double stars move when he was only 16 (in 1889). In 1900, 
Schwarzschild presented a lecture to the German astronomical society in which he theorized 
that space did not act like a regular three-dimensional box. It warped in strange ways, pulled 
and pushed by gravity. Schwarzschild called it “the curvature of space.” 

Five years later, Einstein published his energy equation and his theory of relativity, 
which also talked of the curvature of space. In 1916, while serving in the German army on 
the Russian front during World War I, Schwarzschild was the first to solve Einstein’s equa- 
tions for general relativity. He found that, as a star collapsed into a single point of unimagin- 

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More to Explore 141 


ably dense matter, its gravitational pull would increase so that a particle would have to be 
traveling faster and faster to escape from that gravity (called the escape velocity). 
Schwarzschild’s calculations showed that as a massive star collapsed to a single point of in- 
finitely dense matter, its escape velocity would exceed the speed of light. Nothing would es- 
cape such a collapsed star. It would be as if the star disappeared and no longer existed in our 
universe. 

With these calculations, Schwarzschild had discovered the concept of a black hole. 
The terms we now use to describe a black hole (event horizon, escape velocity, etc) were all 
created by Schwarzschild in 1916. Schwarzschild mathematically “discovered” black 
holes, but he didn’t believe they physically existed. He thought it was only a mathematical 
exercise. 

Fifty years later, astronomers began to seriously search for Schwarzschild’s invisible 
collapsed stars. Astronomers realized that, since a black hole couldn’t actually be seen, the 
only way to detect one was to track unexplained motion of the stars that they could see and 
show that that motion was the result of the gravitational pull of a nearby, unseeable black 
hole. (Astronomer John Wheeler coined the name “black hole” in 1970.) 

In 197 1, calculations by Wheeler’ s team confirmed that the X-ray binary star, Cygnus 
X- 1 , was a star circling a black hole. That was the first time a black hole had ever been phys- 
ically detected. 

It wasn’t until 2004 that a black hole was identified in the Milky Way galaxy, by Pro- 
fessor Phil Charles of the University of Southampton and Mark Wagner of the University of 
Arizona, this one located 6,000 light years away from Earth in our galaxy’s halo. But it was 
Karl Schwarzschild in 1916 who discovered what black holes “looked like” and how to 
locate one. 


/f~\. Fun Facts: Discovered in January 2000, the closest black hole is only 
1,600 light years from Earth and is known as V4641 Sgr. Such normal 
H black holes are several times the mass of the sun. But supermassive black 
holes reside in the hearts of galaxies and can be as massive as several 
hundred million times the mass of the sun. 

More to Explore 

Asimov, Isaac. Black Holes, Pulsars, and Quasars. New York: Gareth Stevens, 2003. 
Davis, Amanda. Black Holes. Minneapolis, MN: Powerkids Press, 2003. 

Jefferies, Daivd. Black Holes. New York: Crabtree Publishing, 2006. 

Nardo, Don. Black Holes. New York: Thomson Gale, 2003. 

Rau, Dana. Black Holes. Mankato, MN: Capstone Press, 2005. 

Sipiera, Paul. Black Holes. New York: Scholastic Library, 1997. 


Year of Discovery: 1921 


Insulin 


What Is It? Insulin is a hormone produced by the pancreas that allows the 
body to pull sugar from blood and burn it to produce energy. 

Who Discovered It? Frederick Banting 


Why Is This One of the 100 Greatest? 

Frederick Banting discovered a way to remove and use the pancreatic “juice” of ani- 
mals to save the lives of diabetic humans. This hormone is called insulin. Its discovery has 
saved millions of human lives. Diabetes used to be a death sentence. There was no known 
way to replace the function of a pancreas that had stopped producing insulin. Banting’s 
discovery changed all that. 

Although insulin is not a cure for diabetes, this discovery turned the death sentence of 
diabetes into a manageable malady with which millions of people live healthy and normal 
lives. 


How Was It Discovered? 

In early 1921, 28-year-old Canadian orthopedic surgeon Frederick Banting developed 
a theory — actually, it was more of a vague idea — for a way to help people suffering from 
diabetes. 

The outer cells of the pancreas produced strong digestive juices. But the inner cells 
produced a delicate hormone that flowed straight into the blood. Muscles got their energy 
from sugars in the bloodstream, which came from food. But the body couldn’t pull sugar out 
of the bloodstream without that hormone from the inner cells of the pancreas. 

When the inner cells of a person’s pancreas stopped making that hormone, their mus- 
cles couldn’t draw sugar from the bloodstream, and the bloodstream became overloaded 
with sugar and struggled to get rid of it through excess urination. The body dehydrated; and 
the patient became deathly ill. This condition was called diabetes. 

In 1920 there was no cure for diabetes. It was always fatal. 

Researchers had tried obtaining the pancreatic hormone (which they referred to as 
“juice”) from animals. But when a pancreas was ground up, the digestive juices from the 
outer cells were so strong that they destroyed the delicate juice from the inner cells before it 
could be used. 

Banting read an article by Dr. Moses Barron that described the fate of several patients 
in whom a blockage had developed in the ducts carrying pancreatic outer cell digestive 


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juices to the stomach. These strong acids had been trapped in the outer cells of the pancreas 


and had destroyed those cells. The cells literally shut down and dried up. 

Banting wondered if he could intentionally kill the outer pancreatic cells of an animal 
and then harvest its inner cell juice for use by diabetic humans. 

His plan was simple enough. Operate to tie off the ducts from a dog’s pancreatic outer 
cells to the stomach, wait the eight weeks Dr. Barron had mentioned in his article, and hope 
that the outer cells had dried up and died. Finally, in a second operation, he would harvest 
the dog’s pancreas and see if it still contained life-giving inner cells and their precious juice. 
He would artificially create diabetes in another dog s and see if the pancreatic fluid from the 
first dog could keep it alive. 

With no funding. Banting talked his way into the use of a lab and six test dogs. The sur- 
gery was simple enough. Now he had to wait eight weeks for the outer cells to die. 

However, early in week six the diabetic dog slid into a coma. This was the last stage 
before death. Banting couldn’t wait any longer. He operated on one of the other dogs, suc- 
cessfully removing its pancreas. He ground up this tissue and extracted the juice by dissolv- 
ing it in a chloride solution. 

He injected a small amount of this juice into the diabetic dog. Within 30 minutes the 
dog awakened from its coma. Within two hours it was back on its feet. In five hours it began 
to slide back down hill. With another injection it perked up, with enough energy to bark and 
wag its tail. 

Banting was ecstatic. His hunch had been right! 

Dr. John Marcum named the juice, “insulin” during the two years that he and Dr. 
Banting searched for a way to create this precious juice without harming lab dogs — a feat 
they eventually accomplished. 


Bankston, John. Frederick Banting and the Discovery of Insulin. Hockessin, DE: 
Mitchell Lane, 2001. 

Bliss, Michael. Discovery of Insulin. Chicago: University of Chicago Press, 1994. 

Fox, Ruth. Milestones in Medicine. New York: Random House, 1995. 

Li, Alison. J. B. Collip and the Evolution of Medical Research in Canada. Toronto: 
McGill-Queens University Press, 2003. 

Mayer, Ann. Sir Frederick Banting. Monroe, WI: The Creative Co., 1994. 

Stottler, J. Frederick Banting. New York: Addison-Wesley, 1996. 



A Fun Facts: In 1922 a 14-year-old boy suffering from type I diabetes was 
/ the first person to be treated with insulin. He showed rapid improvement. 


More to Explore 


Neurotransmitters 


Year of Discovery: 1921 


What Is It? Chemical substances that transmit nerve impulses between 
individual neuron fibers. 

Who Discovered It? Otto Loewi 


Why Is This One of the 100 Greatest? 

Like cracking the genetic code, like the creation of the atomic bomb, the discovery of 
how the brain’s system of neurons communicates is one of the fundamental science devel- 
opments of the twentieth century. 

Nerves signal sensations to the brain; the brain flashes back commands to muscles and 
organs through nerves. But how? Otto Loewi’s discovery of neurotransmitters (the chemi- 
cals that make this communication possible) revolutionized the way scientists think about 
the brain and even what it means to be human. Neurotransmitters control memory, learning, 
thinking, behavior, sleep, movement, and all sensory functions. This discovery was one of 
the keys to understanding brain function and brain organization. 


How Was It Discovered? 

In 1 888 German anatomist Heinrich Walder-Hartz was the first to propose that the ner- 
vous system was a separate network of cells. He named these nerve fibers neurons. He con- 
cluded that the ends of individual nerve cells approached each other closely, but didn’t 
actually touch. In 1893 Italian scientist Camillo Colgi used a new method for staining cells 
that brought out exceptionally fine detail under a microscope and proved that Walder-Hartz 
was correct. 

Walder-Hartz ’s discovery, however, created a scientific controversy. If neurons didn’t 
actually touch, how did they communicate? Some scientists argued that signals had to be 
sent electrically, since electrical currents existed in the brain. Some argued that nerve sig- 
nals had to be sent chemically since there were no solid electrical connections between indi- 
vidual neurons. Neither side could prove its position. 

Otto Loewi was born in Frankfurt, Germany, in 1873. He wanted to become an art his- 
torian but buckled under family pressure and agreed to attend medical school. After barely 
passing his medical examination, Loewi worked in the City Hospital in Frankfurt. How- 
ever, he became depressed by the countless deaths and great suffering of tuberculosis and 
pneumonia patients left to die in crowded hospital wards because there was no therapy for 
them. 


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Loewi quit medical practice and turned to pharmacological research (the study of 
drugs and their effects on human organs). Over the next 25 years ( 1 895 to 1920) he studied 
how different human organs responded to electrical and chemical stimuli. His papers re- 
ported on many human organs including the kidney, pancreas, liver, and brain. 

By 1920 Loewi was focusing much of his attention on nerves. He was convinced that 
chemicals carried signals from one nerve fiber to the next. But, like other researchers, he 
couldn’t prove it. 

Loewi later said that the answer came to him in a dream. It was the night before Easter 
Sunday, 1921. Loewi woke up with a start around midnight and scribbled notes about the 
dream’s idea. The next morning he was unable to read his scrawled notes. Nor could he re- 
member what the dream had been about. All he could remember was that the notes and the 
dream were critical. 

The next night he awoke at 3:00 A.M. from the same dream, remembering it clearly. He 
didn’t dare go back to sleep. He rose and drove to his lab, where he performed the simple ex- 
periment from his dream — an experiment that has become famous. 

Loewi surgically removed the still-beating hearts from two frogs and placed each in its 
own container of saline (salt) solution. He left the autonomic nerve (the Vagus nerve) at- 
tached to heart number one, but not to the second heart. When he applied a tiny electrical 
current to heart number 1 ’ s Vagus nerve, the heart slowed down. When he then allowed 
some saline solution from container 1 to flow into container 2, the second heart slowed 
down to match the slower rate of the first heart. 

Electricity could not have affected the second heart. It had to be some chemical re- 
leased into the saline solution by heart l’s Vagus nerve that then communicated with and 
controlled heart 2. Loewi had proved that nerve cells communicate with chemicals. Loewi 
called this chemical vagusstoff. 

A friend of Loewi’s, Englishman Henry Dale, was the first to isolate and decode this 
chemical’s structure, which we now call acetylcholine. Dale coined the name 
neurotransmitters for this group of chemicals that nerves use for communication. 

/fV; Fun Facts: The longest nerve cell in your body, the sciatic nerve, runs 
\Ly from your lower spine to your foot, roughly two to three feet in length! 

More to Explore 

Adler, Robert. Medical Firsts. New York: John Wiley & Sons, 2004. 

Lanzoni, Susan. A Lot of Nerve. New York: Thomson Gale, 2006. 

Masters, Roger, ed. The Neurotransmitter Revolution. Cairo: Southern Illinois Uni- 
versity Press, 1996. 

Valenstein, Elliot. The War of the Soups and the Sparks: The Discovery of 
Neurotransmitters and the Dispute Over How Nerves Communicate. New York: 
Columbia University Press, 2005. 

Webster, Roy. Neurotransmitters, Drugs and Brain Function. New York: John Wiley 
& Sons, 2001. 


Human Evolution 

Year of Discovery: 1924 


What Is It? Humanoids evolved first in Africa and, as Darwin had postulated, 
developed from the family of apes. 

Who Discovered It? Raymond Dart 


Why Is This One of the 100 Greatest? 

Humans have always wondered how we came to be on this planet. Virtually every cul- 
ture and religion has created myths to explain the creation of humans. In the early twentieth 
century, most scientists believed that the first humans appeared in Asia or Eastern Europe. 
Then Dart discovered the Taung skull and provided the first solid evidence both of an Afri- 
can evolution of the first humanoids and a fossil link between humans and apes, substantiat- 
ing one part of Darwin’s theories. This discovery redirected all of human evolutionary 
research and theory and has served as a cornerstone of science’s modern beliefs about the 
history and origin of our species. 


How Was It Discovered? 

Raymond Dart was born in Queensland, Australia, in 1893 on a bush farm where his 
family was straggling to raise cattle. He excelled in school and received scholarships to study 
medicine, specializing in neural anatomy (the anatomy of skull and brain). In 1920 he gained 
a prestigious position as assistant to Grafton Elliot Smith at the University of Manchester, 
England. But their relationship soured and, in 1922, shortly after his thirtieth birthday, Dart 
was sent off to be a professor of anatomy at the newly formed University of Witwatersrand in 
Johannesburg, South Africa. Dart arrived feeling bitterly betrayed and outcast. 

In 1924 Dart learned of several fossil baboon skulls that had been found at a nearby 
limestone quarry at Taung. Dart asked that they be sent to him along with any other fossils 
found at the site. He did not anticipate finding anything particularly interesting in these fos- 
sils, but the new university’s anatomical museum desperately needed anything it could get. 

The first two boxes of fossil bones were delivered to Dart’s house one Saturday after- 
noon in early September 1924, just as he was dressing for a wedding reception to be held at 
his house later that afternoon. He almost set the boxes aside. But curiosity made him open 
them there in his driveway. The first box contained nothing of particular interest. 

However, on top of the heap of rock inside the second box lay what he instantly recog- 
nized as undoubtedly a cast or mold of the interior of a skull — a fossilized brain (rare 
enough in and of itself). Dart knew at first glance that this was no ordinary anthropoid (ape) 

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More to Explore 147 


brain. It was three times the size of a baboon’s brain and considerably larger than even an 
adult chimpanzee’s. 

The brain’s shape was also different from that of any ape Dart had studied. The 
forebrain had grown large and bulging, completely covering the hindbrain. It was closer to a 
human brain and yet, certainly, not fully human. It had to be a link between ape and human. 

Dart feverishly searched through the box for a skull to match this brain so that he could 
put a face on this creature. Luckily he found a large stone with a depression into which the 
brain cast fit perfectly. He stood transfixed in the driveway with the brain cast and 
skull-containing rock in his hands, so long that he was late for the wedding. 

He spent the next three months patiently chipping away the rock matrix that covered 
the actual skull, using his wife’s sharpened knitting needles. Two days before Christmas, a 
child’ s face emerged, complete with a full set of milk teeth and permanent molars still in the 
process of erupting. The Taung skull and brain were that of an early humanlike child. 

Dart quickly wrote an article for: Nature magazine describing his discovery of the early 
humanoid and showed how the structure of the skull and spinal cord connection clearly 
showed that the child had walked upright. Dart claimed to have discovered the “missing 
link” that showed how humans evolved in the African plain from apes. 

The scientific community were neither impressed with Dart’s description nor convinced. 
All European scientists remained skeptical until well-respected Scotsman Robert Broom dis- 
covered a second African skull in 1938 that supported and substantiated Dart’s discovery. 


Avi-Yonah, Michael. Dig This! Denver, CO: Runestone Press, 1993. 

Gundling, Tom. First in Line: Tracing Our Ape Ancestry. New Haven, CT: Yale Uni- 
versity Press, 2005. 

Leakey, Mary. Disclosing the Past. New York: McGraw-Hill, 1996. 

Leroi-Gourhan, Andre. The Hunters of Prehistory. New York: Atheneum, 2000. 
McIntosh, Jane. The Practical Archaeologist. New York: Facts on File, 1999. 
Phillipson, David W. African Archaeology. Cambridge: Cambridge University Press, 


Scheller, William. Amazing Archaeologists and Their Finds. New York: Atheneum, 


Tanner, Nancy Makepeace. On Becoming Human. Cambridge: Cambridge University 
Press, 2001. 

Tattersall, I. The Fossil Trail: How We Know What We Think We Know About Human 
Evolution. New York: Oxford University Press, 1995. 

Trinkaus, E. The Neanderthals: Changing the Image of Mankind. New York: Alfred 
A. Knopf, 1992. 

Wheelhouse, Frances. Dart: Scientist and Man of Grit. Hornsby, Australia: 
Transpareon Press, 2001. 



Ti Fun Facts: Darwin believed that humanoids emerged in Africa. No one 
/ believed him for 50 years, until Dart uncovered his famed skull in 1924. 


More to Explore 


2001 . 


1994. 


Quantum Theory 


Year of Discovery: 1925 


What Is It? A mathematical system that accurately describes the behavior of 
the subatomic world. 

Who Discovered It? Max Born 


Why Is This One of the 100 Greatest? 

In the first 20 years of the twentieth century, physics buzzed with the incredible dis- 
covery of the subatomic world. Long before microscopes were powerful enough to allow 
researchers to see an atom, scientists used mathematics to probe into the subatomic world of 
electrons, protons, and alpha and beta particles. 

Albert Einstein, Werner Heisenberg, Max Planck, Paul Dirac, and other famed re- 
searchers posed theories to explain this bizarre new territory. But it was quiet, unassuming 
Max Bom who discovered a unified quantum theory that systematically, mathematically 
described the subatomic world. 

Max Born’s gift to the world was a brand-new field of study we call “quantum me- 
chanics” that is the basis of all modern atomic and nuclear physics and solid state mechan- 
ics. It is because of Max Born that we are now able to quantitatively describe the world of 
subatomic particles. 


How Was It Discovered? 

Einstein published his general theory of relativity in 1905. So, for the last year and a 
half of his university study, 25-year-old Gottingen University mathematics student Max 
Born lived in a world abuzz with the wonder, implications, and potential of Einstein’s bold 
and revolutionary theory. 

Bitterly frustrated that he couldn’ t find a postgraduate position that would allow him to 
continue his studies of the subatomic world, Born returned home to live in his childhood 
room. Working alone for two years at the desk he used for homework as a boy, he tried to 
apply his mathematical teachings to the problems of subatomic relativity as described in 
Einstein’s theory. Through this work. Max Born discovered a simplified and more accurate 
method of calculating the minuscule mass of an electron. 

Born wrote a paper on his findings that generated an offer for a full-time position at 
Gottingen University. Two weeks after he started, the job evaporated. Born limped back 


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More to Explore 149 


home for another full year of independent study and a second paper, a review of the mathe- 
matical implications of Einstein’s relativity, before he was offered a lecturing position at 
Gottingen University. 

However, the only available research funding was designated for the study of the vibra- 
tional energy in crystals. Deeply disappointed, feeling excluded from the grand hunt for the 
structure of the atom. Born launched his study of crystals. For five years Born and two assis- 
tants collected, grew, sliced into paper-thin wedges, studied, measured, and analyzed crystals. 

In 1915 Born shifted to the University of Berlin to work with physics giant Max 
Planck. Planck and Einstein were at the hub of the race to unravel and understand the sub- 
atomic world. Born brought his mathematical superiority and his understanding of crystals 
to aid their efforts. It was a classic case of finally being in the right place at the right time 
with the right background. 

Theories abounded to explain the peculiar behavior of subatomic particles. But no one 
was able to write down the mathematics that proved and described those theories. The prob- 
lem had mystified the greatest minds in the scientific world for almost 20 years. 

It occurred to Born that the quantum phenomena physicists found so troubling in elec- 
trons looked remarkably similar to the behavior of the crystals he had studied for five years. 

In 1916 Born started to apply what he had learned with crystals to the immense and 
complex numerical problem that surrounded subatomic particles. The work stretched the 
available mathematical tools to their limits. The effort extended over nine years of work on 
blackboards, on note pads, and with slide rules. 

In 1925 Born completed work on “Zur Quantenmechanik,” or “On Quantum Mechan- 
ics.” The phrase had never been used before. The paper exploded across the scientific 
world. It clearly, mathematically, laid out the fundamentals that Einstein, Planck, Dirac, 
Niels Bohr, Hermann Minkowski, Heisenberg, and others had talked about. It concretely 
explained and described the amazing world of subatomic particles. 

“Quantum mechanics” became the name of the new field of study that focused on a 
quantitative description of subatomic phenomena. Max Born became its founder. 


Baggott, Jim. The Meaning of Quantum Theory. New York: Oxford University Press, 1998. 

Born, Max. Physics in My Generation. London: Cambridge University Press, 1996. 

Clive, Barbara. The Questioners: Physicists and the Quantum Theory. New York: 
Thomas Crowell, 1995. 

Gribbin, John. In Search of Schrodinger’s Cat: Quantum Physics and Reality. New 
York: Bantam Books, 1984. 

Keller, Alex. The Infancy of Atomic Physics. Oxford: Clarendon Press, 1993. 

Tanor, Joseph, ed. McGraw-Hill Modem Men of Science. New York: McGraw-Hill, 1986. 
Wasson, Tyler, ed. Nobel Prize Winners. New York: H. W. Wilson, 1987. 



Fun Facts: In the bizarre quantum world, many of our “normal” laws do not 
apply. There, objects (like electrons) can be (and regularly are) in two differ- 
ent places at once without upsetting any of the laws of quantum existence. 


More to Explore 


Expanding Universe 


Year of Discovery: 1926 


What Is It? The universe is expanding. The millions of galaxies move ever 
outward, away from its center. 

Who Discovered It? Edwin Hubble 


Why Is This One of the 100 Greatest? 

Hubble’s twin discoveries (that there are many galaxies in the universe — not just the 
Milky Way — and that all of those galaxies are traveling outward, expanding the universe) 
rank as the most important astronomical discoveries of the twentieth century. These discov- 
eries radically changed science’s view of the cosmos and of our place in it. Hubble’s work 
also represents the first accurate assessment of the movement of stars and galaxies. 

The discovery that the universe is expanding and ever changing for the first time al- 
lowed scientists to ponder the universe’s past. This discovery led directly to the discovery 
of the Big Bang and the origin of the universe as well as to a new concept of time and of the 
future of the universe. 


How Was It Discovered? 

In 1923 Edwin Hubble was a tall, broad-shouldered, powerful astronomer of 33 who, 
10 years earlier, had almost chosen a career as a professional boxer over astronomy. Hubble 
had been hired in 1920 to complete and operate the Mt. Wilson Observatory’s mammoth 
100-inch telescope in California — the largest telescope in the world. 

In the early twentieth century, the universe was thought to contain one galaxy — the 
Milky Way — plus scattered stars and nebulae drifting around its edges. Hubble decided to 
use the giant 100-inch telescope to study several of these nebulae and picked Andromeda as 
his first target — and he made the two most important astronomical discoveries of the 
twentieth century. 

This giant telescope’s power showed Hubble that Andromeda wasn’t a cloud of gas (as 
had been thought). It was a dense cluster of millions of separate stars! It looked more like a 
separate galaxy. 

Then Hubble located several Cepheid stars in Andromeda. Cepheid stars pulse. The 
beat of their pulse is always a direct measure of the absolute amount of light given off by the 
star. By measuring their pulse rate and their apparent amount of light, scientists can deter- 
mine the exact distance to the star. 


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More to Explore 151 


Andromeda lay 900,000 light-years away. That proved that Andromeda was a separate 
galaxy. It lay too far away to be a fringe part of the Milky Way. 

Within six months, Hubble had studied and measured 18 other nebulae. They were all 
separate galaxies, ranging from five to 100 million light-years from Earth. Astronomers 
were shocked to learn that the universe was so big and that it likely contained thousands of 
separate galaxies. 

But Hubble was just beginning. He had noticed a consistent red shift when studying 
the light emitted from these distant nebulae. 

Scientists had discovered that each element (helium, hydrogen, argon, oxygen, etc.) 
always emitted energy in a characteristic set of specific frequencies that identified the ele- 
ment’s presence. If they made a spectrograph (a chart of the energy radiated at each separate 
frequency) of the light being emitted from a star, the lines on the spectrograph would tell 
them which elements were present in the star and in what relative quantities. 

Hubble found all the common spectrograph lines for helium, hydrogen, and so forth 
that were normally found in a star. But all the lines on his graph were at slightly lower fre- 
quencies than normal. It was called a red shift because when visible light frequencies are 
lowered, their color shifts toward red. If their frequency is raised, their color shifts toward 
blue (a blue shift). 

Over the next two years, Edwin Hubble conducted exhaustive tests of the 20 galaxies 
he had identified. He found that every one (except Andromeda) was moving away from 
Earth. More startling, the galaxies moved away from us and away from each other. Every 
galaxy he studied was speeding straight out into open space at speeds of between 800 and 
50,000 kilometers per second! 

The universe was expanding, growing larger every second as the galaxies raced out- 
ward. It was not a static thing that had remained unchanged since the beginning of time. In 
each moment the universe is different than it has ever been before. 

(f~\\ Fun Facts: Because the universe is expanding, every galaxy in existence 
y is moving away from our own Milky Way — except for one. Andromeda, 
If our nearest neighbor, is moving on a collision course with the Milky 
Way. Don’t worry, though: the collision won’t occur for several million 
years. 


More to Explore 

Barrow, John. The Origin of the Universe. New York: Basic Books, 1994. 

Burns, Ruth Ann. Stephen Hawking’s Universe (video). New York: WNET, 1997. 

Haven, Kendall, and Donna Clark. 100 Most Popular Scientists for Young Adults. 
Englewood, CO: Libraries Unlimited, 1999. 

Munitz, Milton, ed. Theories of the Universe: From Babylonian Myths to Modern Sci- 
ence. New York: Free Press, 2001. 

Rees, Martin. “Exploring Our Universe and Others.” Scientific American 281, no. 6 
(December 1999): 78-83. 


152 Expanding Universe 


Sandage, Alan. The Hubble Atlas of Galaxies. Washington, DC: Carnegie Institution 
of Washington, 1994. 

Sharov, Alexander S., and Igor D. Novikov. Edwin Hubble: The Discoverer of the Big 
Bang Universe. New York: Cambridge University Press, 1993. 

Wilson, Robert. Astronomy through the Ages. Princeton, NJ: Princeton University 
Press, 1998. 


Uncertainty Principle 


Year of Discovery: 1927 


What Is It? It is impossible to know the position and motion of an elementary 
particle (e.g., an electron) at the same time. 

Who Discovered It? Werner Heisenberg 


Why Is This One of the 100 Greatest? 

Werner Heisenberg is famed worldwide for discovering the Uncertainty Principle, 
which states that it is impossible to determine both the position and momentum (motion) of 
an elementary particle at the same time since the effort to determine either would change the 
other in unpredictable ways. This pivotal theorem marked a fundamental turning point in 
science. For the first time it was no longer possible to precisely and completely measure or 
observe the world. At a certain point, Heisenberg showed, scientists had to step back and 
take the mathematical equations describing the world on faith. 

The Heisenberg Uncertainty Principle also undermined the position of cause and ef- 
fect as a most basic and unassailable foundation block of scientific research, a position it 
had enjoyed for over 2,500 years. Aat an elementary particle level, every cause had only a 
fixed probability of creating an anticipated effect. 


How Was It Discovered? 

Opening the mail in his Helgoland, Germany, home, in the fall of 1926, Werner 
Heisenberg found a letter from famed physicist Max Planck. The letter glowed with praise 
for Heisenberg’s paper presenting the “matrix mechanics” Heisenberg had developed. It 
was Heisenberg’s fifth congratulatory letter from a famed physicist that week. 

Every letter hailed Heisenberg’s matrix mechanics and talked about its “vast poten- 
tial.” They called it “new and exciting” and “extremely valuable.” 

But Werner Heisenberg’s deep sense of unease was not relieved by these letters. Bur- 
ied in his matrix equations, Heisenberg had detected what he thought was a hard limit to sci- 
ence. If true, it would be the first time science had been told it was impossible to be more 
precise. A deep dread rumbled the foundations of Heisenberg’s scientific beliefs. Yet there 
it was in black and white. If he was right, science had reached an unscalable wall. 

The great physics debate at that time centered on the image of an atom. Was it a ball of 
protons sumounded by shells of particle electrons, as Niels Bohr claimed, or were electrons 
really waves of energy flowing around the central nucleus, as others proposed? It occurred 
to Heisenberg to forget speculation and begin with what was known — that when electrons 

153 



154 Uncertainty Principle 


(whatever they were) became excited, they released quanta of energy at specific character- 
istic frequencies. Heisenberg decided to develop equations to describe and predict the end 
result, the spectral lines of this radiated energy. 

He turned to matrix analysis to help him derive equations with terms such as fre- 
quency, position, and momentum along with precise ways to mathematically manipulate 
them. The resulting equations, while yielding good results, seemed strange and unwieldy. 
Uncertain of their value, Heisenberg almost burned the final paper. Instead he sent a copy to 
someone he had studied with and trusted, Wolfgang Pauli. Pauli instantly recognized the 
value of Heisenberg’s work and notified other physicists. 

Heisenberg’s discovery, called matrix mechanics, gained him instant fame. But 
Heisenberg was deeply bothered by what happened when he completed his matrix calcula- 
tions. Heisenberg noticed that, because of the matrix nature of the calculations, the value of 
a particle’s position could affect the value he had to use for its momentum (the particle’s 
motion), and vice versa. 

While dealing with imprecision was not new, it was new to realize that the better he 
knew one term, the more it would add imprecision to another. The better he knew position, 
the less he knew about momentum. The more precisely he could determine momentum, the 
less he would know about position. 

Heisenberg had accidentally discovered the principle of uncertainty. In one sweeping 
discovery he destroyed the notion of a completely deterministic world. Hard limits sud- 
denly existed on science’s ability to measure and observe. For the first time, there were 
places scientists could not go, events they could never see. Cause and effect became cause 
and chance-of-effect. At the most fundamental level the very approach to physical science 
was altered. Research was made instantly more complex, and yet new doors and avenues to 
understanding and progress were opened. Heisenberg’s Uncertainty Principle has been a 
guiding foundation of particle research ever since. 


Daintith, John, et al., eds. Biographical Encyclopedia of Scientists, Second Edition, 
Volume 1. Philadelphia: Institute of Physics Publishing, 1994. 

Eggenberger, David, ed. The McGraw-Hill Encyclopedia of World Biography, Vol- 
ume 5. New York: McGraw-Hill, 1993. 

Gillispie, Charles, ed. Dictionary of Scientific Biography, Volume XV. New York: 
Charles Scribner’s Sons, 1998. 

Hoffman, Banesh. The Strange Story of the Quantum. Cambridge, MA: Harvard Uni- 
versity Press, 1999. 

Rensberger, Boyce. How the World Works: A Guide to Science’s Greatest Discover- 
ies. New York: William Morrow, 1994. 



Fun Facts: Werner’s best subjects were mathematics, physics, and reli- 
/ gion, but his record throughout his school career was excellent all round. 
| In fact his mathematical abilities were such that in 1917 (when he was 16) 
he tutored a family friend who was at the university studying calculus. 


More to Explore 


Speed of Light 


Year of Discovery: 1928 


What Is It? The speed at which light travels — a universal constant. 
Who Discovered It? Albert Michelson 


Why Is This One of the 100 Greatest? 

In the late 1 800s discovering the true the speed of light had only minor importance be- 
cause astronomers were the only ones who used this number. (Distances across space are 
measured in light-years — how far light travels in one year’s time.) Since their measure- 
ments were only approximations anyway, they could accept a 5 percent (or even 10 percent) 
error in that value. 

2 

Then Albert Einstein created his famed energy-matter equation, E = me'. Instantly the 
speed of light, “c,” became critical to a great many calculations. Discovering its true value 
jumped to the highest priority. Light speed became one of the two most important constants 
in all physics. A 1 percent error, or even a 0.1 percent error, in “c” was suddenly unaccept- 
ably large. 

But the problems of discovering the true speed of light — a speed faster than any clock 
could measure or other machines could detect — were enormous. Albert Michelson invented 
half a dozen new precision devices and, after 50 years of attempts, was the first human to ac- 
curately measure light speed. His discovery earned Michelson the first Nobel Prize to be 
given to an American physicist. 


How Was It Discovered? 

This was a discovery that was dependent on the invention of new technology and new 
equipment — just as Galileo’s discovery of moons around other planets was dependent on 
the invention of the telescope. 

In 1928, 74-year-old Albert Michelson struggled to make one last try to accurately 
measure the speed of light and discover the true value of “c” in Einstein’s famed equation. 
He had designed, financed, and completed a dozen attempts over the previous 50 years. 
Michelson was determined this time to measure the speed of light with no more than a 0.001 
percent error. That value would finally be accurate enough to support essential nuclear 
physics calculations. 

Four years earlier, Michelson had turned to the famed gyroscope manufacturer, Elmer 
Sperry, to improve upon the equipment available for his measurements. Now in 1928, the 
third, and latest, round of equipment improvements was represented by a small octagonal 


155 



156 Speed of Light 


cylinder that had just been driven in a thickly padded crate up the bumpy dirt road to the top 
of Mt. Baldy in California — Michelson’s test site. 

The experiment Michelson designed was simple. He shone a light onto this small mir- 
rored cylinder as it rotated at a high speed, driven by a motor (also invented by Sperry) ca- 
pable of maintaining an exact speed of rotation. At some point as the mirror turned, it would 
be perfectly aligned to reflect this light beam toward a stationary, curved mirror at the back 
of the room. However, the rotating mirror would only reflect light back to that mirror for a 
very small fraction of a second before it rotated on. 

This back wall mirror thus got short pulses of light from each face of the rotating mir- 
ror. Each pulse reflected through a focusing lens and out through an opening in the wall 22 
miles to Mt. San Antonio. There it bounced off a mirror, through a second focusing lens, 
and straight back to Mt. Baldy. Here the light pulse once again hit the back wall mirror, and 
finally reflected back to the rotating cylinder. 

Even though each pulse of light would complete this 44-mile journey in less than 
1/4000 of a second, the rotating cylinder would have already turned some by the time that 
light pulse got back from Mt. San Antonio. Returning light would reflect off the rotating 
mirror and hit a spot on the shed wall. The angle from the cylinder to that spot would tell 
Michelson how far the mirror had rotated while a pulse of light made the 44-mile 
round-trip. That would tell him how fast the light had traveled. 

While it all sounded simple, it meant years of work to improve the necessary equip- 
ment. Sperry created a better light so that it would last through 44 miles of travel. He created 
a more accurate motor drive so that Michelson would always know exactly how fast the 
small cylinder was turning. 

Sperry designed smoother focusing lenses and a better mirrored cylinder — one that 
wouldn’t vibrate or distort its mirrored sides under the tremendous forces of high-speed 
rotation. 

Michelson switched on the motor and light. Faster than eyes could see, the light stream 
shot out to Mt. San Antonio and back. It bounced off the rotating cylinder and onto the far 
wall. 

From the cylinder’s rotational speed and the placement of that mark on the wall, 
Michelson calculated the speed of light to be 186,284 miles per second — less than 2 mph 
off of the modern estimate — an error of less than 0.001 percent. With this discovery, scien- 
tists in the fields of physics, nuclear physics, and high-energy physics were able to proceed 
with the calculations that led to nuclear energy and nuclear weapons. 


Daintith, John, et ah, eds. Biographical Encyclopedia of Scientists, Second Edition, 
Volume 1. Philadelphia: Institute of Physics Publishing, 1994. 

Garraty, John, ed. Encyclopedia of American Biography. New York: Harper & Row, 



Ti Fun Facts: Traveling at light speed, your ship could go from New York 
J to Los Angeles 70 times in less than one second. In that same one second 
• you could make seven and a half trips around the earth at the equator. 


More to Explore 


2000 . 


More to Explore 157 


Year of Discovery: 1928 


Penicillin 


What Is It? The first commercially available antibiotic drug. 
Who Discovered It? Alexander Fleming 


Why Is This One of the 100 Greatest? 

Penicillin has saved millions of lives — tens of thousands during the last years of World 
War II alone. The first antibiotic to successfully fight bacterial infections and disease, peni- 
cillin was called a miracle cure for a dozen killer diseases rampant in the early twentieth 
century. 

Penicillin created a whole new arsenal of drugs in doctors’ toolkits to fight disease and 
infection. It opened the door to entire new families and new generations of antibiotic drugs. 
Penicillin started the vast industry of antibiotic drugs and ushered in a new era of medicine. 


How Was It Discovered? 

In 1928, 47-year-old Scottish bom Alexander Fleming was named chief biochemist at 
St. Mary’s Hospital in London and given a basement laboratory tucked in next to the boiler 
room. 

As the staff bacteriologist, he grew (or “cultured”) bacteria in small, round, glass 
plates for hospital study and experiment. Using microscopic amounts of a bacterium (often 
collected from a sick patient), he grew enough of each to determine why the patient was sick 
and how best to fight the infection. Small dishes of deadly staphylococci, streptococci, and 
pneumococci bacteria were lined and labeled across the one lab bench that stretched the 
length of Fleming’s lab. 

Molds were the one great hazard to Fleming’s lab operation. Fleming’s lab alternated 
between being drafty and stuffy, depending on the weather and how hard the boiler worked 
next door. His only ventilation was a pair of windows that opened at ground level to the 
parklike gardens of the hospital. Afternoon breezes blew leaves, dust, and a great variety of 
airborne molds through those windows. It seemed impossible to keep molds from drifting 
into, and contaminating, most of the bacteria Fleming tried to grow. 

On September 28, 1928, Fleming’s heart sank as he realized that a prized dish of pure 
(and deadly) staphylococci bacteria had been ruined by a strange, green mold. The mold 
must have floated into the dish sometime early the previous evening and had been multiply- 
ing since then. Greenish mold fuzz now covered half the dish. 


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More to Explore 159 


Fleming grunted and sighed. Then he froze. Where this strange green mold had grown, 
the staphylococci bacteria had simply disappeared. Even bacteria more than an inch from 
the mold had turned transparent and sickly. 

What kind of mold could destroy one of the most hearty, tenacious, and deadly bacteria 
on earth? No other substance then known to man could attack staphylococci so successfully. 

It took two weeks for Fleming to isolate and culture enough of the tough green mold to 
complete an identification: Penicillium notatum. Within a month he had discovered that the 
mold secreted a substance that killed bacteria. He began to call this substance “penicillin.” 

Through culture dish experiments he discovered that penicillin could easily destroy all 
the common human-killing bacteria — staphylococci, streptococci, pneumococci, even the 
toughest of all, the bacilli of diphtheria. The only bacterium penicillin fought but did not de- 
stroy was the weak, sensitive bacterium that caused influenza (flu). 

Fleming spent six months testing penicillin on rabbits to establish that the drug was 
safe for human use before, in late 1929, announcing the discovery of his miracle mold that 
had drifted in the window. 

However, penicillin was difficult and slow to grow. It worked wonders but was avail- 
able in such small quantities that it did little practical good. In 1942 Dorothy Hodgkin, a 
British researcher, developed a new process, called X-ray crystalography, to decipher the 
structure of a penicillin molecule. It took her 15 months and thousands of X-ray images of 
the molecules in a penicillin crystal to identify each of the 35 atoms in a penicillin molecule. 
Dr. Hodgkin was awarded the 1964 Nobel Prize for her work. 

American doctors Howard Florey and Ernst Chain were able to use Hodgkin’s map to 
synthetically produce penicillin molecules in mass production beginning in 1943. For their 
effort, Florey and Chain were awarded the 1945 Nobel Price in Medicine jointly with Alex- 
ander Fleming, the discoverer of penicillin. 

(f~f | Fun Facts: American researchers in Peoria, Illinois, were able to de- 
\C/ velop commercial production of penicillin first, because two of penicil- 
1P lin’s favorite foods turned out to be a strain of local Illinois corn and 
rotting cantaloupes, donated by a Peoria market. Those food bases 
helped researchers increase their production of penicillin from 400 mil- 
lion to over 650 billion units a month 

More to Explore 

Bankston, John. Alexander Fleming and the Story of Penicillin. Hockessin, DE: 
Mitchell Fane, 2001. 

Birch, Beverly. Alexander Fleming: Pioneer with Antibiotics. New York: Thomson 
Gale, 2002. 

Hantula, Richard. Alexander Fleming. New York: Gareth Stevens, 2003. 

Parker, Steve. Alexander Fleming. Portsmouth, NH: Heinemann, 2001. 

Snedden, Robert. Scientists and Discoveries. Portsmouth, NH: Heinemann, 2001. 

Tocci, Salvatori. Alexander Fleming: The Man Who Discovered Penicillin. Berkeley 
Heights, NJ: Enslow, 2002. 


Year of Discovery: 1929 


Antimatter 


What Is It? Antimatter are particles of the same mass and composition as pro- 
tons and electrons, but with an opposite electrical charge. 

Who Discovered It? Paul Dirac 


Why Is This One of the 100 Greatest? 

Science fiction space ships are regularly powered by antimatter drives. Futuristic 
bombs are designed around antimatter. Yet neither you nor anyone you’ve ever met has 
even once seen a particle of antimatter. Antimatter does not come in fist-sized chunks, but 
as stray, individual subatomic particles. 

Paul Dirac is considered by many to be the greatest British theoretical physicist since 
Newton. Dirac was the first to predict the necessary existence of positrons and antiprotons, 
or antimatter. The concept of antimatter provided a new avenue of research and understand- 
ing in physics. Dirac’s antimatter discovery has become the theoretical framework for mod- 
ern particle physics. Modern cosmologists and physicists are able to extend and apply the 
precepts of quantum physics, quantum electrodynamics, and quantum mechanics in large 
part because of Dirac’s discovery. 


How Was It Discovered? 

Shy, retiring, and secretive by nature, 21 -year-old Cambridge University physics 
graduate student Paul Dirac had made few friends, but had gained a reputation for mathe- 
matical brilliance. 

By 1923, the theories of relativity and quantum mechanics were well-established, but 
their limits and the exact implications and meaning were not. Quantum mechanics, the 
study of systems so small that Newtonian physics breaks down, was based on the assump- 
tion that subatomic matter acts both like particles and waves. The contradictions and para- 
doxical implications of this assumption and the mathematics used to try to describe it were 
drawing physics toward a crisis. 

Through a series of cunning research efforts and precise, articulate papers, Dirac be- 
gan to chip away at these inconsistencies, bringing clarity and reason to what had previ- 
ously seemed to be chaotic uncertainty. Fie improved the methods to calculate a particle’s 
speed as defined by “Eddington’s equations”. Fie resolved the discrepancies of the 
covariance of Niels Bohr’s frequency condition. 


160 



More to Explore 161 


Still as a graduate student, he published five important papers and turned his focus to 
the more general problem of uniting quantum mechanics (the laws governing the mi- 
cro-world of elementary particles) and relativity (the laws governing the macro-world of 
planetary and universal gravitation). To this work Dirac brought his engineer’ s ability to ac- 
cept and use approximations when exact calculations were not possible and where exact 
measurements did not exist. This talent allowed Dirac to venture into new areas of analysis 
whose lack of exact measurements had stopped previous researchers. 

Dirac worked mostly in the world of advanced mathematics for these studies. He used 
the results of a number of lab studies conducted by other researchers to test and verify his 
equations and mathematical models. 

Through completion of his doctoral work and through the first five years of his work as 
a researcher at Cambridge, Dirac struggled to resolve the apparent incompatibility of these 
two major systems of thought and analysis. By 1929 Dirac had realized that his calculations 
required that several subatomic particles had to exist that had never been detected or 
thought of before. In order for the equations that he had developed and tested against lab re- 
sults to work, an entire set of new particles had to exist. These new particles would mimic 
the mass and composition of the known particles, but would have the opposite electrical 
charge. 

Protons and neutrons were known. Dirac concluded that negatively charged particles 
of equivalent mass must also exist. The existence of this antiproton, or antimatter, was con- 
firmed 25 years later. 

Similarly, Dirac concluded that if an electron existed, positively and neutrally charged 
particles of similar mass (positron and neutrino respectively) must also exist. The existence 
of positrons was confirmed two years later, in 1932. Neutrinos were positively identified in 
the mid-1970s, but their mass was not confirmed until work done by Japanese researchers in 
1998. 

Dirac thus discovered the existence of antimatter and proved that the particles we can 
see, touch, and deal with represent only half of the kinds of particles that inhabit our uni- 
verse. In so doing, Dirac moved science closer to an accurate view of the physical world. 

(f~^\ Fun Facts: When matter converts to energy, some residue is always left. 
Only part of the matter can be converted into energy. Not so with anti- 
ip matter. When antimatter collides with matter, 100 percent of both matter 
and antimatter are converted into usable energy. A gram of antimatter 
would carry as much potential energy as 1,000 space shuttle external 
tanks carry. 

More to Explore 

Daintith, John, et al., eds. Biographical Encyclopedia of Scientists, Second Edition, 
Volume 1. Philadelphia: Institute of Physics Publishing, 1994. 

Devine, Elizabeth, ed. The Annual Obituary, 1983. Chicago: St. James Press, 1990. 

Dirac, Paul. The General Theory of Relativity. New York: John Wiley & Sons, 1995. 

. The Principles of Quantum Mechanics. London: Cambridge University Press, 

1998. 


162 Antimatter 


Kragh, Helge. Dirac: A Scientific Biography. New York: Cambridge University Press, 
1996. 

Pais, Abraham. Paul Dirac: The Man and His Work. New York: Cambridge Univer- 
sity Press, 2005. 

Scheller, Bill. Spaced Out!: An Extreme Reader . . . from Warps and Wormholes to 
Killer Asteroids. New York: Penguin, 1999. 

Wasson, Tyler, ed. Nobel Prize Winners. New York: H. W. Wilson, 1987. 


Year of Discovery: 1932 


Neutron 


What Is It? A subatomic particle located in the nucleus of an atom with the 
mass of a proton but no electrical charge. 

Who Discovered It? James Chadwick 


Why Is This One of the 100 Greatest? 

The discovery of neutrons has been hailed as a major landmark of twentieth-century 
science. First, this discovery completed our understanding of the structure of atoms. Sec- 
ond, because they have no electrical charge, neutrons have been by far the most useful parti- 
cles for creating nuclear collisions and reactions and for exploring the structure and reaction 
of atoms. Neutrons were used by Ernest Lawrence at UC Berkeley to discover a dozen new 
elements. Neutrons were essential to the creation of nuclear fission and to the atomic bomb. 

How Was It Discovered? 

Since the discovery that a subatomic world existed (in 1901), only the two electrically 
charged particles — proton and electron — had been discovered. Scientists assumed that 
these two particles made up the whole mass of every atom. 

But there was a problem. If atoms were made up of protons and electrons, spin didn’t 
add up correctly. The idea that each subatomic particle possessed a “spin” was discovered 
in 1925 by George Uhlenbeck and Samuel Goudsmit in Germany. For example, a nitrogen 
atom has an atomic mass of 14 (a proton has a mass of 1) and its nucleus has a positive elec- 
trical charge of +7 (each proton has a charge of + 1); to balance this positive charge, seven 
electrons (charge of -1 each) orbit around the nucleus. But somehow, seven additional elec- 
trons had to exist inside the nucleus to cancel out the positive electrical charge of the other 
seven protons. 

Thus, 21 particles (14 protons and 7 electrons) should reside in each nitrogen nucleus, 
each with a spin of either +Vi or -Vi. Because 2 1 is an odd number of particles, no matter how 
they combined, the total spin of each nitrogen nucleus would have to have a Vi in it. But the 
measured spin of a nitrogen nucleus was always a whole integer. No half. Something was 
wrong. 

Ernest Rutherford proposed that a proton-electron must exist and that a nitrogen nu- 
cleus has seven protons and seven proton-electrons (for 14 particles — an even number — 
and the correct spin total). But it was only theory. He had no idea of how to detect a pro- 
ton-electron since the only known way to detect a particle was to detect its electrical charge. 

163 



164 Neutron 


Enter James Chadwick. Born in 1 89 1 in England, Chadwick was another of the crop of 
physicists who learned their atomic physics under Rutherford. By the mid- 1920s Chadwick 
was obsessed with the search for Rutherford’s uncharged proton-electron. 

In 1928 Chadwick began to use beryllium for his experiments. Beryllium was a small, 
simple atom with an atomic mass of 9. He bombarded beryllium with alpha particles from 
polonium (a radioactive element) and hoped that some beryllium atoms would be struck by 
alpha particles and burst apart into two new alpha particles (each with a mass of 4). 

If that happened, these two alpha particles would carry all of the electrical charge of 
the original beryllium nucleus, but not all of its mass. One atomic unit of mass (the mass of a 
proton) would be left over from beryllium’s original mass of 9. But that last proton-sized 
particle from the breakup of this beryllium nucleus would have no electrical charge. It 
would therefore have to be the proton-electron (now called neutron) Chadwick sought. 

If this experiment worked, Chadwick would create a stream of neutrons along with al- 
pha particles. However, it took three years for Chadwick to find a way to detect the presence 
of any neutrons he created in this way. He used a strong electrical field to deflect alpha parti- 
cles (all electrically charged). Only uncharged particles would continue straight along the 
target path. 

Happily, Chadwick found that something was still smashing into a block of paraffin 
wax he placed at the end of the target path. That “ something ” hit the paraffin hard enough to 
break new alpha particles loose from the wax. That something had to have come from the 
collision of alpha particles with beryllium atoms, had to be at least the size of a proton (to 
break new alpha particles loose in the paraffin), and couldn’t have an electrical charge since 
it wasn’t deflected by the electrical field. It had to be a neutron. 

Chadwick had discovered the neutron. He had proved that they existed. But it was 
Rutherford, not Chadwick, who named it neutron for its neutral electrical charge. 


Adler, Robert. Science Firsts, New York: John Wiley & Sons, 2002. 

Bortz, Fred. Neutron. Cherry Hill, NJ: Rosen Publishing Group, 2004. 

Brown, Andrew. The Neutron and the Bomb: A Biography of Sir James Chadwick. 
New York: Oxford University Press, 1997. 

Bunch, Bryan. The History of Science and Technology. New York: Houghton Mifflin, 



T, Fun Facts: A neutron has nearly 1,840 times the mass of the electron. 
/ How does that size compare with a proton? 


More to Explore 


2004. 


Garwin, Laura. A Century of Nature: Twenty-One Discoveries That Changed Science 
and the World. Chicago: University of Chicago Press, 2003. 


Cell Structure 


Year of Discovery: 1933 


What Is It? The first accurate map of the many internal structures that make up 
a living cell. 

Who Discovered It? Albert Claude 


Why Is This One of the 100 Greatest? 

Albert Claude was the first scientist to develop procedures for isolating and studying 
individual structures within a cell. He is the one who mapped the inner organization and ac- 
tivity of a cell and its many components. He is rightly called the founder of modern cell 
biology. 

Although he never graduated from high school, Claude pioneered the use of centrifuge 
techniques and the electron microscope for the study of living cells. He discovered a dozen 
key components of cells, identified the function of other cell substructures, and laid the 
groundwork for a whole new field of cellular biology. 


How Was It Discovered? 

Albert Claude received only a third-grade education before he was forced to quit 
school and get a mill job. After serving in the Belgian army during World War I, Claude was 
able to study medicine in college when the Belgian government allowed any returning sol- 
dier to attend college — even though the University of Liege was less than eager to accept an 
illiterate country soldier. 

During his studies, Claude submitted a lengthy research proposal to the Rockefeller 
Institute for Medical Research in New York. It was accepted and Claude immigrated to 
America. 

Claude proposed to study live cancer cells and discover how the disease was transmit- 
ted. His proposal called for him to separate cells into different components for individual 
study, something that had never been tried before. There were no established procedures or 
equipment for such an operation. Claude had to scrounge crude equipment from machine 
and butcher shops. He used commercial meat grinders to pulverize samples of chicken can- 
cerous tumors that he suspended in a liquid medium. He used a high-speed centrifuge to 
separate the ground-up cells into their various subparts — heaviest on the bottom, lightest on 
top. He called the procedure cell fractionation . 

He now had test tubes filled with layers of goo and mud. Since no one had ever sepa- 
rated cell subparts before, it took Claude several years of study and practice to determine 

165 



166 Cell Structure 


what each isolated layer was and to learn how to successfully isolate the tumor agent from 
the rest of the cell. Claude’s chemical analysis showed this agent to be a ribonucleic acid 
(RNA), a known constituent of viruses. This was the first evidence that cancer was caused 
by a virus. 

Claude decided to continue using cell fractionation to study healthy cells. Working 
full-time in his laboratory over the next six years using a centrifuge and a high-powered mi- 
croscope, Claude was able to isolate and describe the cell nucleus (the structure that houses 
the chromosomes), organelles (specialized microscopic structures within a cell that act like 
organs), mitochondria (tiny rod-shaped granules where respiration and energy production 
actually happen), and ribosomes (the sites within cells where proteins are formed). 

Claude was mapping a new world that had only been guessed at before. Still, his view 
was limited by the power of his microscope. In 1942 the Rockefeller Institute was able to 
borrow the only electron microscope in New York, used by physicists attempting to probe 
inside an atom. This scope was capable of magnifying objects one million times their 
original size. 

However, the scope also bombarded a sample with a powerful beam of electrons in or- 
der to create an image. Such an electron stream destroyed fragile living tissue. Claude spent 
1 8 months developing successful methods to prepare and protect cell samples to withstand 
the electron microscope. By mid- 1943 Claude had obtained the first actual images of the in- 
ternal structure of a cell, images previously unthinkable. In 1945 Claude published a cata- 
log of dozens of new cell structures and functions never before identified. 

The names of the scientists who broke the barrier of an atom and discovered what lay 
inside (e.g., Marie Curie, Max Born, Niels Bohr, Enrico Fermi, and Werner Heisenberg) are 
well known and revered. Albert Claude single-handedly broke through the barrier of a cell 
wall to discover and document a universe of subparts and activity inside. 


Daintith, John, ed. Biographical Encyclopedia of Science. 2d ed. Philadelphia: 
Thomson Scientific, 1994. 

Devine, Elizabeth, ed. The Annual Obituary, 1978. Chicago, St. James Press, 1999. 

Kordon, Claude. The Language of the Cell. New York: McGraw-Hill, 1992. 

Rensberger, Boyce. Life Itself: Exploring the Realm of the Living Cell. New York: Ox- 
ford University Press, 1997. 

Wasson, Tyler, ed. Nobel Prize Winners. New York: H. W. Wilson, 1987. 



A Fun Facts: There are more than 250 different types of cells in your body. 
/ yet they all started as, and grew out of, one single cell — the fertilized egg 


cell. 


More to Explore 


The Function of Genes 


Year of Discovery: 1934 


What Is It? Beadle discovered how genes perform their vital function. 
Who Discovered It? George Beadle 


Why Is This One of the 100 Greatest? 

Genes are strung along chromosomes and contain directions for the operation and 
growth of individual cells. But how can a molecule of nucleic acid (a gene) direct an entire 
complex cell to perform in a certain way? George Beadle answered this critical question and 
vastly improved our understanding of evolutionary genetics. 

Beadle discovered that each gene directs the formation of a particular enzyme. En- 
zymes then swing the cell into action. His discovery filled a huge gap in scientists’ under- 
standing of how DNA blueprints are translated into physical cell-building action. Beadle’s 
groundbreaking work shifted the focus of the entire field of genetics research from the qual- 
itative study of outward characteristics (what physical deformities are created by mutated 
genes) to the quantitative chemical study of genes and their mode of producing enzymes. 


How Was It Discovered? 

George Beadle was supposed to be a farmer. He was born on a farm outside Wahoo, 
Nebraska, in 1903. But a college study of the genetics of hybrid wheat hooked Beadle on the 
wonder of genetics. Genetics instantly became his lifelong passion. 

In 1937, at the age of 34, Beadle landed an appointment with the genetics faculty at 
Stanford University. Stanford wanted to develop their study of biochemical genetics. The 
study of genetics was 80 years old. But biochemical genetics, or the molecular study of how 
genetics signals were created and sent to cells, was still in its infancy. Beadle teamed with 
microbiologist Edward Tatum to try to determine how genes exercise their controlling 
influence. 

In concept their work was simple. In practice it was painstakingly tedious and demand- 
ing. They searched for the simplest life form they could find, choosing the bread mold 
Neurospora because its simple gene structure had been well documented. They grew trays 
upon trays of colonies of Neurospora in a common growth medium. Then Beadle and 
Tatum bombarded every colony with X-rays, which were known to accelerate genetic mu- 
tations. Within 12 hours most colonies continued to grow normally (they were unmutated), 
a few died (X-rays had destroyed them), and a precious few lived but failed to thrive (gene 
mutations now made them unable to grow). 

167 



168 The Function of Genes 


The interesting group was this third one because it had undergone some genetic muta- 
tion that made it impossible for the mold to grow on its own. If Beadle and Tatum could dis- 
cover exactly what this mutated mold now needed in order to grow, they would learn what 
its mutated gene had done on its own before it was damaged. 

Beadle and Tatum placed individual spores from one of these colonies into a thousand 
different test tubes, each containing the same standard growth medium. To each tube they 
added one possible substance the original mold had been able to synthesize for itself but that 
the mutated mold might not be producing. Then they waited to see which, if any, would 
begin to thrive. 

Only one tube began to grow normally — tube 299, the one to which they had added vi- 
tamin B 6 . The mutation to the mold’s gene must have left the mold unable to synthesize vi- 
tamin B 6 and thus unable to grow. That meant that the original gene had produced 
something that made the cells able to synthesize the vitamin on their own. The second step 
of Beadle and Tatum’s experiment was to search for that something. 

Beadle found that when he removed, or blocked, certain enzymes the mold stopped 
growing. He was able to trace these enzymes back to genes and to show that the mutated 
gene from tube 299 no longer produced that specific enzyme. 

Through this experiment Beadle discovered how genes do their' job. He proved that 
genes produce enzymes and that enzymes chemically direct cells to act. It was a discovery 
worthy of a Nobel Prize. 

(f~\ Fun Facts: Humans have between 25,000 and 28,000 genes. Different 
w genes direct every aspect of your growth and looks. Some do nothing at 
IP all. Called recessive genes, they patiently wait to be passed on to the next 
generation, when they might have the chance to become dominant and 
control something. 

More to Explore 

Beadle, George. Language of Life: An In troduction to the Science of Genetics. New 
York: Doubleday, 1966. 

Davern, Cedric. Genetics: Readings from Scientific American. San Francisco: W. H. 
Freeman, 1998. 

Maitland Edey, and Donald Johanson. BLUEPRINTS: Solving the Mystery of Evolu- 
tion. New York: Penguin Books, 1996. 

Moritz, Charles, ed. Current Biography Yearbook, 1990. New York: H.W. Wilson, 
1991. 

Tanor, Joseph, ed. McGraw-Hill Modern Men of Science. New York: McGraw-Hill, 
1996. 

Wasson, Tyler, ed. Nobel Prize Winners. New York: H. W. Wilson, 1987. 


Year of Discovery: 1935 


Ecosystem 


What Is It? The plants, animals, and environment in a given place are all inter- 
dependent. 

Who Discovered It? Arthur Tansley 


Why Is This One of the 100 Greatest? 

Many scientists over the centuries had studied the relationship of various species to 
their climate and environment. They studied elements of ecology. However, it wasn’t until 
1935 that Arthur Tansley realized that all species in a given environment were intercon- 
nected. Grasses affected top carnivores and the bugs that decomposed dead animals, and 
fallen trees affected grasses and bushes. 

Tansley discovered that every organism is part of a closed, interdependent system — an 
ecosystem. This discovery was an important development in our understanding of biology 
and launched the modern environmental movement and the science of ecology. 


How Was It Discovered? 

Arthur Tansley was the person who saw the big picture and discovered that all ele- 
ments of a local ecological system were dependent upon each other, like individual threads 
in a tightly spun web. But he was not the first person to study ecology. 

Aristotle and his student, Theophrastus, studied the relationships between animals and 
their environment in the fourth century B.C. In 1805, German scientist Alexander von 
Humbolt published his studies of the relationship between plant species and climate. He 
was the first to describe vegetation zones. 

Alfred Wallace, a competitor of Darwin’s, was the first to propose (in 1 870) a “geogra- 
phy” of animal species, relating animals to their climate and geography. In the early nine- 
teenth century, French scientist Antoine Lavoisier discovered the nitrogen cycle. This cycle 
linked plants, animals, water, and atmosphere into a single interdependent cycle by tracing 
how nitrogen cycles through the environment. What science needed was for someone to 
recognize that all of these individual pieces fit together like pieces in a jigsaw puzzle. 

Arthur Tansley was born into a wealthy family in London in 1 87 1 . He earned a degree 
in botany and lectured throughout his working career at University College in London and 
then at Cambridge. Tansley was active in promoting English plant ecology and helped 
found the British Ecological Society. 


169 



170 Ecosystem 


In the late 1920s Tansley conducted a massive plant inventory of England for the Eco- 
logical Society. During this study, Tansley began to focus not just on the list of plants he set 
out to create, but on the relationships between this vast list of plants. Which grasses were 
found with which others? With which bushes and weeds? Which grasses populated lowland 
meadows? Which were found on craggy mountainsides? And so forth. 

By 1930 Tansley had realized that he couldn’t fully analyze the relationships between 
plants without considering the effects of animals. He began to inventory and map the many 
browsers — animals that ate grasses. Soon he realized that any study of these browser ani- 
mals was woefully incomplete unless he included an inventory of the carnivores that 
controlled browser populations. 

Then he realized that he had to include recyclers and decomposers (organisms that 
broke down decaying plant and animal matter into the basic chemical nutrients for plants). 
Finally he added the physical (inorganic) environment (water, precipitation, climate, etc.). 

Tansley had realized by 1935 that each area he studied represented an integrated, en- 
closed local system that acted as a single unit and included all organisms in that given area 
and their relationship to the local inorganic environment. It was a breathtakingly grand con- 
cept. Each species was linked to all others. What happened to one affected all others. 

Water, sunlight, and some inorganic chemicals entered the system from the outside. 
All living organisms inside the closed ecological system fed off each other, passing food up 
and then back down the food web. 

Tansley shortened the name from ecological system to ecosystem. That term and that 
concept, however, did not gain popularity until 1953 when American scientist Eugene 
Odum published Fundamentals of Ecology, a book that explained the concept of, and used 
the term, ecosystem. 


Anker, Peder. Imperial Ecology: Environmental Order in the British Empire, 
1845-1945. Cambridge, MA: Harvard University Press, 2002. 

Ball, Jackie. Ecology. New York: Gareth Stevens, 2003. 

Dorling Kindersley Staff. Ecology: Eyewitness. New York: DK Publishing, 2000. 
Lane, Brian. Ecology. New York: DK Publishing, 2005. 

Stone, Lynn. Forests. Vero Beach, FL: Rourke Publishing, 2004. 



Fun Facts: An important ecosystem service that most people don’t think 
about is pollination. Ninety percent of the world’s food crops would not 
exist without pollinators like bees, bats, and wasps. 


More to Explore 


Weak and Strong Force 


Years of Discovery: 1937 and 1983 


What Is It? The last two of the four fundamental physics forces of nature. 

Who Discovered It? Carlo Rubbia (weak force) and Hideki Yukawa 
(strong force) 


Why Is This One of the 100 Greatest? 

For several centuries scientists thought that gravity and electromagnetic forces gov- 
erned the universe. Then twentieth-century physicists found atomic nuclei composed of 
positively charged protons. Why didn’t they fly apart since positive electrical forces repel 
each other? Further, why did some atoms naturally radioactively decay while others did 
not? 

Many physicists proposed that two new forces (weak and strong) must exist. In 1935, 
Flideki Yukawa discovered the strong force. It was not until 1983 that Carlo Rubbia discov- 
ered the two particles that defined the weak force. 

These discoveries completed our understanding of the four forces that govern the mi- 
croscopic quantum world and direct whole clusters of galaxies. The weak and strong forces 
form the foundation of quantum physics. 


How Was It Discovered? 

Newton mathematically defined gravity in 1666. Faraday, Oersted, and Maxwell de- 
fined electromagnetism in the early nineteenth century. Scientists thought that these two 
forces ruled the universe. 

Flowever, twentieth-century physicists realized that neither of these forces could hold 
an atom together. Electromagnetic repulsion of like charges (protons) should rip every 
atomic nucleus apart. Why did nuclei and atoms exist? Other scientists realized that some 
force had to be responsible for the decay of radioactive nuclei. 

Scientists theorized that two new forces had to exist: the strong force (the force that 
held atomic nuclei together) and the weak force (that created radioactive decay). No evi- 
dence existed to prove that either force actually existed. Though many searched, by the late 
1930s no one had detected or proved the existence of either force. 

In 1936 Flideki Yukawa reasoned that, since neither the weak nor the strong force had 
ever been detected, they must act over a range that was smaller than the diameter of an 
atomic nucleus. (Thus, they would be undetectable outside of that tiny space.) He began a 


171 



172 Weak and Strong Force 


series of experiments in which he smashed protons (hydrogen nuclei) with neutrons to see if 
the collision products would give him a hint about how the strong force worked. 

Yukawa noticed the consistent production of large (for subatomic particles), 
short-lived particles called pi-mesons (a kind of gluon ) from these collisions. That meant 
that pi-mesons existed inside the nucleus of atoms since that is where they sprang from. 

Yukawa proposed that mesons, in general, represented the attractive force called the 
strong force. Noting that photons (which represented electromagnetic force) and gravitons 
(which represented gravitational force) were both virtually massless, he proposed that the 
greater the mass of these tiny particles, the shorter the distance over which they exerted their 
effects. 

He proposed that the short-range strong force came about from the exchange of the 
massive meson particles between protons and neutrons. Yukawa could describe the mesons 
he believed represented the strong force, but he could not physically produce one. 

In 1947 Lattes, Muirhead, Occhialini, and Powell conducted a high-altitude experi- 
ment, flying photographic emulsions at 3,000 meters. These emulsions revealed the pion, 
which met all the requirements of the Yukawa particle. 

We now know that the pion is a meson, both types of the tiny particles called gluons, 
and that the strong interaction is an exchange of mesons between quarks (the subatomic 
particles that make up protons and neutrons). 

The weak force proved harder to confirm through actual discovery. It was not until 
1983 that Carlo Rubbia, at the European research center, CERN, first discovered evidence 
to prove the existence of the weak force. After completing initial work in the 1970s that al- 
lowed Rubbia to calculate the size and other physical properties of the missing particles re- 
sponsible for carrying the weak force, Rubbia and a CERN team set out to find these 
particles. 

Rubbia then proposed that the large synchrotron at CERN be modified so that beams 
of accelerated protons and antiprotons could be made to collide head-on, releasing ener- 
gies great enough for weak boson particles to materialize. In 1983 his experiments with 
the colliding-beam apparatus isolated two short-lived particles, the W and Z particles. 
Rubbia was able to show that these particles were the carriers of the so-called weak force in- 
volved in the radioactive decay of atomic nuclei. 

The four fundamental forces of nature (and the particles that carry and create each of 
these forces) had finally been discovered, to complete the standard model that has carried 
physicists into the twnety-first century. 

Fun Facts: Hideki Yukawa was the first Japanese to win the Nobel prize. 

More to Explore 

Cottingham, W. N. An Introduction to Nuclear Physics. New York: Cambridge Uni- 
versity Press, 2001. 

Gale Reference Team. Biography: Hideki Yukawa (1907-1981 ). New York: Gale Re- 
search, 2004. 


More to Explore 173 


Galison, Peter. How Experiments End. Chicago: University of Chicago Press, 1997. 

Lilley, J. S. Nuclear Physics. New York: John Wiley & Sons, 2001. 

Taubes, Gary. Nobel Dreams: Power, Deceit, and the Ultimate Experiment. Seattle, 
WA: Microsoft Press, 1996. 

Watkins, Peter. Story of the W and Z. New York: Cambridge University Press, 1996. 
Yukawa, Hideki. Yukawa, 1907-1981 . Berlin, PA: Berlin Publishing, 1997. 


Metabolism 


Year of Discovery: 1938 


What Is It? Krebs discovered the circular chain of chemical reactions that 
turns sugars into energy inside a cell and drives metabolism. 

Who Discovered It? Hans Adolf Krebs 


Why Is This One of the 100 Greatest? 

Muscles do the work for your body. You eat food and — somehow — it turns into en- 
ergy that your muscles burn to move. But how? How does this thing called metabolism 
work? 

The process of metabolism in human bodies is so important to our understanding of 
human anatomy that three Nobel prizes have been given to people who contributed to our 
understanding of it. The third was given to Hans Adolf Krebs, who finally solved the mys- 
tery and discovered how our bodies metabolize food into energy. It was one of the great 
medical discoveries of the twentieth century. 


How Was It Discovered? 

British physiologist Archibald Hill believed that muscles should produce heat when 
they contracted. By 1913, he had developed ways to measure changes as small as 3/1000 of 
a degree. To his surprise he discovered that, during muscle contraction, no heat was pro- 
duced nor was any oxygen consumed. 

Five years later, German Otto Meyerhof discovered that, during muscle contraction, 
the chemical glycogen disappears and lactic acid appears. He named this process anaero- 
bic, from the Greek words meaning “without oxygen.” He later discovered that oxygen was 
used in the muscle cells later to break down lactic acid. Other researchers found that when 
they added any of four different carbon-based acids to muscle tissue slices, it stimulated the 
tissue to absorb oxygen. 

Even though these discoveries seemed important, they created as much confusion 
about the process of how muscles work as they provided answers. Someone had to make 
sense of these different, seemingly confusing studies. 

Hans Krebs was born in 1900 in Germany, the son of a surgeon. He studied chemistry 
and medicine and was then hired to conduct research at Cambridge University. He focused 
this research on the chemical process of muscle metabolism. 

Beginning in 1937, Krebs studied pigeon liver and breast muscle tissue. He was able to 
measure the amounts of certain groups of acids — some that contain four carbon atoms each 


174 



More to Explore 175 


and other groups of acids that contain six carbon atoms each — that were created when sug- 
ars are oxidized (combined with oxygen). He also noted that this process created carbon di- 
oxide, water, and energy. 

These results were confusing. What did all these chemicals have to do with simple me- 
tabolism of sugars into energy? Krebs saw citric acid being broken down and yet at the same 
time, citric acid was being produced. The same was true for a number of other acids. 

Slowly Krebs realized that the process worked in a circle — a circle with seven separate 
chemical steps. It started with citric acid. Each step produced the chemicals and acids that 
were needed for the next step in the cycle. In the last step, citric acid was produced to start 
the cycle all over again. 

The cycle continues endlessly in each of our cells. Along the way, glucose molecules 
(sugars) supplied by the blood are consumed. Two waste products were produced by this 
seven-step cycle: carbon dioxide and free hydrogen atoms. These hydrogen atoms then 
combine with oxygen and a form of high-energy phosphate to create water and ATP, the 
chemical that stores energy for cells just like a battery. 

Sugar molecules enter the cycle, and carbon dioxide, water, and ATP to power the 
cells exit the cycle. By 1938 Krebs had unraveled this amazingly complex and yet amaz- 
ingly efficient seven-step chemical cycle — specifically designed to accomplish a seemingly 
simple task: convert sugars in the blood into energy for muscle cells. Amazingly, each mus- 
cle cell in our bodies creates these seven sequential reactions, each sparked by a different 
enzyme, every minute of every day. And Hans Krebs discovered how it works. 


Bailey, Donna. Energy for Our Bodies. New York: Steck-Vaughn, 1999. 

Curran, Christina. Metabolic Processes and Energy Transfers: An Anthology of Cur- 
rent Though. Cherry Hill, NJ: Rosen Central, 2005. 

Hewitt, Sally. Full of Energy. New York: Scholastic Library Publishing, 1998. 

Holmes, Frederick. Hans Krebs: Architect of Intermediary Metabolism. New York: 
Oxford University Press, 1999. 

Nichols, Peter. Biology of Oxygen. Jefferson, NC: McFarland, 1997. 



A Fun Facts: The average person’s body could theoretically generate 100 
/ watts of electricity using a bio-nano generator, a nano-scale electrochem- 
I ical fuel cell that draws power from blood glucose much the same way 
the body generates energy using the Krebs Cycle. 


More to Explore 


Year of Discovery: 1938 


Coelacanth 


What Is It? A living fish species thought to be extinct for 80 million years. 
Who Discovered It? J. L. B. Smith 


Why Is This One of the 100 Greatest? 

The scientific world was shocked in 1938 when a coelacanth was discovered. All scien- 
tists believed that this fish had been extinct for 80 million years. No fossil or trace of it had been 
found in more recent strata. This discovery shattered the belief that the known fossil record rep- 
resented a complete and accurate record of the arrival and extinction of species on this planet. It 
confirmed that the deep oceans hold biological mysteries still untapped and unimagined. 

Equally important, the coelacanth is a “living fossil.” Unchanged for over 400 million 
years, this fish is a close relative of the fish that, hundreds of millions of years ago, was the 
first creature to crawl out of the sea onto land — the first amphibian, the first land creature. 
Thus, the coelacanth is one of our earliest ancestors. This discovery has been called the 
most important zoological find of the twentieth century, as amazing as stumbling upon a 
living dinosaur. 


How Was It Discovered? 

In the late 1930s, 32-year-old Margorie Courtenay-Latimer was the curator of a tiny 
museum in the port town of East London on the Indian Ocean side of South Africa. Local 
fishing boat captain Hendrick Gossen always called her when he returned to port with un- 
usual or interesting fish that she might want for her collection. Usually these finds turned 
out to be nothing important. 

On December 23, 1938, just before Margorie closed the museum for her Christmas holi- 
day, she got a call from Gossen. She almost didn’t go. She wanted to go home to wrap presents. 

However, she decided to swing quickly by the piers on her way. She climbed onto 
Gossen’ s boat and noticed a blue fin protruding from beneath a pile of rays and sharks 
heaped upon the deck. She had never seen such an iridescent blue on a fish fin before and 
she literally gasped. 

Pushing the overlaying fish aside revealed what she described as “the most beautiful 
fish I ever saw.” It was five feet long, pale mauve-blue with iridescent markings. She had no 
idea what the fish was, but knew it was unlike anything previously caught in local waters. 
Besides the unique coloring, this fish’s fins did not attach to a skeleton, but to fleshy lobes 
on the sides of its body as if they could be used to support the fish and allow it to crawl. 

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More to Explore 177 


Back in her small museum office with the precious fish, she thumbed through refer- 
ence books and found a picture that led her to a seemingly impossible conclusion. It looked 
exactly like a prehistoric fish that had been extinct for 80 million years. 

She mailed a detailed description of the fish to professor J. L. B. Smith, a chemistry 
and biology teacher at Rhodes University, 50 miles south of East London. Unfortunately, 
Smith had already left for Christmas vacation and did not read her message until January 3, 
1939. He immediately wired back, “IMPORTANT! PRESERVE SKELETON, ORGANS, 
AND GILLS OF FISH DESCRIBED!” 

By this time, however, the fish’s innards (including gills) had been thrown away and 
the fish had been mounted for museum display. Smith reached Margorie’s museum on Feb- 
ruary 16 and immediately confirmed Margorie’s tentative identification. The fish was a 
coelacanth (SEE-la-kanth), a fish believed to be extinct for over 80 million years. 

The find was important not only because coelacanths had been thought extinct for such 
a long time, but also because this recent specimen showed that they had remained un- 
changed for over 400 million years ! 

But Smith needed a second, complete specimen to be sure. He posted a £100 (British) 
reward for a complete specimen. Yet none were found. It was a tortuously long 14 years be- 
fore, on December 21, 1952, fishing captain Eric Hunt was handed a complete coelacanth 
by native fishermen on the island of Comoro, between Zanzibar and Africa. 

Hunt carried this second complete coelacanth to Smith and the discovery was con- 
firmed. Smith published the discovery in his 1956 book on Indian Ocean marine species and 
rattled the imagination of the world. If an 80-million-year-old creature could lurk unde- 
tected in oceans, what else swam, hidden, through the depths? World interest in marine 
science skyrocketed. 

Since 1956, over 200 coelacanths have been caught in the same general area. But it 
was the vigilant observation of Margorie Courtenay-Latimer and the knowledge of J. L. B. 
Smith that kept this monumental discovery from being just another fish dinner. 

(f~\ Fun Facts: The International Union for the Conservation of Nature and 
vL / Natural Resources recently surveyed 40,177 species. Of that total, 
U 16, 1 19 are now listed as threatened with extinction. This includes one in 
three amphibians and a quarter of the world’s coniferous trees, as well as 
one in eight birds and one in four mammals. 

More to Explore 

Smith, J. L. B. J. L. B. Smith Institute of Ichthyology: 50 Years of Ichthyology . London: 
Cassell, 1994. 

Thompson, Keith. Living Fossil: The Story of the Coelacanth. New York: W. W. 
Norton, 2001. 

Walker, Sally. Mystery Fish: Secrets of the Coelacanth. New York: Lerner Group, 
2005. 

Weber, Valerie. Coelacanth. New York: Gareth Stevens, 2005. 

Weinberg, Samantha. Fish Caught in Time: The Search for the Coelacanth. New 
York: HarperCollins, 2001. 


Nuclear Fission 

Year of Discovery: 1939 


What Is It? The discovery of how to split uranium atoms apart and produce 
vast amounts of energy. 

Who Discovered It? Lise Meitner 


Why Is This One of the 100 Greatest? 

Nuclear fission — the splitting of uranium atoms to produce energy — was one of the 
great physics advances of the twentieth century. It answered one of the great physics puz- 
zles of the age and opened the door to the atomic age. This discovery is the basis for nuclear 
power and nuclear weapons. 

For her discoveries, Lise Meitner has been called “the most significant woman scien- 
tist of this century.” Enrico Fermi deserves credit for many major discoveries in the field of 
atomic physics. But Fermi is most famous for creating the world’s first self-sustained nu- 
clear reaction. Fermi put Meitner’s discovery to practical use and is thus the founding father 
of nuclear power. 


How Was It Discovered? 

Fise Meitner and Otto Hahn were researchers at the Kaiser Wilhelm Institute in Berlin, 
Germany. As part of their study of radioactive elements, Meitner and Hahn had struggled 
for years to create atoms heavier than uranium (transuranic elements). They bombarded 
uranium atoms with free protons. It seemed obvious that some would hit the nucleus and 
stick, creating an element heavier than uranium. But it never worked. 

They had tested their methods with other heavy metals. Each performed exactly as ex- 
pected. Everything worked as Fise’s physics equations said it should — until they reached 
uranium, the heaviest known element. Throughout the 1930s, no one could figure out why 
the experiment always failed with uranium. 

There was no physical reason why heavier atoms couldn’t exist. But in over 100 tries, 
it had never worked. Obviously, something was happening in their experiments that they 
did not understand. They needed a new kind of experiment to show them what really hap- 
pened when they bombarded uranium nuclei with free protons. 

Finally Otto conceived a plan using nonradioactive barium as a marker to continu- 
ously detect and measure the presence of radioactive radium. If uranium decayed into ra- 
dium, the barium would detect it. 


178 



More to Explore 179 


Three more months were consumed with preliminary tests to establish how barium re- 
acted to radioactive radium in the presence of uranium and to remeasure the exact decay 
rates and decay patterns of radium. 

Before they could finish and conduct their actual experiment, Lise had to flee to Swe- 
den to escape the rise of Hitler’s Nazi party. Otto Hahn had to conduct their grand experi- 
ment alone. 

Two weeks after Hahn completed this test, Lise received a lengthy report describing 
his failure. He bombarded uranium with a concentrated stream of protons. But he didn’t 
even get radium. He detected only more barium — far more barium than he started with. Be- 
wildered, he begged Lise to help him figure out what had happened. 

One week later, Lise took a long snowshoe walk through the early winter snows. A 
flash image appeared in her mind of atoms tearing themselves apart. The picture was so 
vivid, so startling, and so strong that she could almost feel the pulsing atomic nuclei and 
smell the sizzle of each atom as it ripped itself apart in her imagination. 

Instantly she knew that she had just been given their answer. Adding extra protons 
must have made the uranium nuclei unstable. They had split apart. One more experiment 
confirmed that, when radioactive uranium is bombarded with free protons, each uranium 
atom split in two, creating barium and krypton. In the process immense amounts of energy 
were released. 

Meitner had discovered the process of nuclear fission. 

Almost four years later, at 2:20 P.M. on December 2, 1942, Enrico Fermi flipped the 
switch that raised hundreds of neutron-absorbing cadmium control rods out of stacks of 
graphite blocks laced with several tons of uranium oxide pellets. Fermi had stacked 42,000 
graphite blocks in an underground squash court situated under the west bleachers of Stagg’s 
field, the University of Chicago football field. It was the world’s first nuclear reactor — the 
product of Meitner’s discovery. The 1945 creation of the atomic bomb was the second ap- 
plication of Meitner’s fission. 


Barron, Rachel. Lise Meitner: Discoverer of Nuclear Fission. New York, Franklin 
Watts, 2000. 

Boorse, Henry, and Floyd Motz. The Atomic Scientist: A Biographical History. New 
York: John Wiley & Sons, 1989. 

Grinstein, Fouise S., Rose K. Rose, and Miriam H. Rafailovich. Women in Chemistry 
and Physics: A Biobiblio graphic Sourcebook. Westport, CT: Greenwood Press, 


Kass-Simon, G., and Patricia Farnes, eds. Women of Science: Righting the Record. 
Bloomington: Indiana University Press, 1990. 

McGrayne, Sharon Bertsch. Nobel Prize Women in Science: Their Lives, Struggles, 
and Momentous Discoveries. New York: Carol Publishing Group, A Birch Fane 
Press Book, 1993. 



^ Fun Facts: After Fise Meitner’ s death, the 109th element on the Periodic 
/ Chart of Elements was named after her: “meitnerium.” 


More to Explore 


1993. 


180 Nuclear Fission 


Sime, Ruth Lewis. Lise Meitner: A Life in Physics. Berkeley: University of California 
Press, 1996. 

Stille, Darlene R. Extraordinary Women Scientists. Chicago: Children’s Press, 1995. 
Wasson, Tyler, ed. Nobel Prize Winners. New York: H. W. Wilson, 1987. 

Yount, Lisa. Twentieth-Century Women Scientists. New York: Facts on File, 1996. 


Blood Plasma 

Year of Discovery: 1940 


What Is It? Plasma is that portion of human blood that remains after red blood 
cells have been separated out. 

Who Discovered It? Charles Drew 


Why Is This One of the 100 Greatest? 

Whole blood can be safely stored for only a few days. That had always meant that 
blood donations had to come from local sources and be given at the time of need. Blood 
couldn’t travel long distances. People with unusual blood types often had to do without dur- 
ing surgery and suffered accordingly. 

Drew discovered the process of separating blood into red blood cells and blood 
plasma. This discovery greatly extended the shelf life of stored blood and has saved thousands 
— and probably millions — of lives. Drew’s discovery made blood hanks practicable. His 
process and discovery are still used by the Red Cross today for its blood donation and stor- 
age program. 


How Was It Discovered? 

The idea of blood transfusions is thousands of years old and was practiced by Roman 
doctors. However, there was a problem: many patients died from the transfusion. No one 
could understand why this happened until Karl Landsteiner discovered the four blood types 
in 1897 (A, B, O, and AB). By 1930, other researchers had further divided these groups into 
eight types by identifying the RH factor for each group (e.g.: 0+, 0-, A+, A-, etc.). 

With these discoveries, blood transfusions became virtually 100 percent safe. But now 
hospitals had to store eight kinds of blood in order to have whatever supply was needed for 
surgeries. However, most donated blood had to be thrown away because it spoiled before 
being used. Some common blood types ran out and patients faced grave danger when they 
had to undergo surgery without it. Blood storage became a critical problem for surgeries 
and hospitals in general. 

Charles Drew was born in mid-summer in 1904 in Washington, D.C. An all-American 
football player at Amherst College, Drew chose to study medicine rather than play sports. 

In 1928 Drew was accepted into medical school at McGill University in Canada (one 
of the few university medical schools to accept blacks in 1928). There Drew studied under 
Dr. John Beattie, a visiting professor from England. In 1930 Beattie and Drew began a 


181 



182 Blood Plasma 


study of ways to extend safe blood storage time from the existing limits of between two and 
six days. This short shelf life drastically limited available blood supplies. 

Drew graduated in 1935 and left the university with little progress having been made. 
In 1938, he took a research position at Columbia University in New York City and contin- 
ued his blood research. There, he developed a centrifuge technique that allowed him to sep- 
arate red blood cells from the rest of blood. This “rest” he called blood plasma. 

He quickly determined that red blood cells contain the unique substances that divide 
blood into the eight blood types. Blood plasma, however, was universal. No matching was 
necessary. Blood plasma from any donor was compatible with any recipient. This made 
plasma especially attractive for blood supplies. 

Drew tested plasma and showed that it lasted far longer than whole blood. Next, he 
showed that red blood cells, separated from plasma, also could be stored longer than whole 
blood. 

In 1939 Drew discovered that plasma could be dehydrated, shipped long distances, 
and then safely rehydrated (reconstituted) by adding water just before surgery. Suddenly 
blood donors could be thousands of miles from recipients. 

In 1940 Drew published his doctorial dissertation. In it he presented his statistical and 
medical evidence that plasma lasted longer than whole blood and detailed the process of 
separating blood into red blood cells and plasma and the process for dehydrating plasma. It 
served as a blueprint for managing the national blood supply. In 1941 Drew created the first 
“bloodmobiles” — trucks equipped with refrigerators — and started the first blood drive (col- 
lected for British airmen and soldiers). 

Drew had discovered plasma and how to safely store blood for long transport, and had 
created a practical system of blood banks and bloodmobiles to collect, process, store, and 
ship blood wherever it was needed. Finally, blood transfusions were both safe and practical. 


Jackson, Garnet. Charles Drew , Doctor. New York: Modem Curriculum Press, 1997. 
Salas, Laura. Charles Drew: Pioneer in Medicine. Mankato, MN: Capstone Press, 


Schraff, Anne. Charles Drew: Pioneer in Medicine. Berkeley Heights, NJ: Enslow, 


Shapiro, Miles. Charles Drew: Founder of the Blood Bank. New York: Steck-Vaughn, 
1997. 

Whitehurst, Susan. Dr. Charles Drew: Medical Pioneer. Chanhassen, MN: Child’s 
World, 2001. 



Fun Facts: Is all blood red? No. Crabs have blue blood. Their blood con- 
tains copper instead of iron. Earthworms and leeches have green blood; 
the green comes from an iron substance called chlorocruorin. Many in- 
vertebrates, such as starfish, have clear or yellowish blood. 


More to Explore 


2006. 


2003. 


Semiconductor transistor 


Year of Discovery: 1947 


What Is It? Semiconductor material can be turned, momentarily, into a super- 
conductor. 

Who Discovered It? John Bardeen 


Why Is This One of the 100 Greatest? 

John Bardeen won his first Nobel Prize for discovering the transistor effect of semi- 
conductor materials. Most materials either conduct electric flow (conductors) or block that 
flow (insulators). But a few materials sometimes permitted some electric flow (semiconduc- 
tors). Though they had been identified by the late 1800s, no one knew the value of semicon- 
ductors until Bardeen discovered the transistor effect. 

The transistor has been the backbone of every computing, calculating, communicat- 
ing, and logic electronics chip and circuit built in the last 50 years. The transistor revolu- 
tionized the worlds of electronics and made most of the modern pieces of essential 
electronic and computing hardware possible. There is no area of life or science that has not 
been deeply affected by this one discovery 


How Was It Discovered? 

John Bardeen was a true child prodigy, skipping fourth, fifth, and sixth grades and re- 
ceiving a master’s degree in physics at 21. With a Ph.D. from Harvard, he taught physics at 
the University of Minnesota until, in 1945, he was hired by Bell Laboratories, a high-tech 
communications and electronics research plant. 

In the fall of 1947 Bardeen joined forces with William Shockley and Walter Brattain, 
who were already studying the possible use of semiconductor materials in electronics. 
Shockley shared the “industrial dream” of freeing electronics from the bulkiness, fragility, 
heat production, and high power consumption of the vacuum tube. To allow semiconduc- 
tors to replace tubes, Shockley had to make semiconductor material both amplify and rec- 
tify electric signals. All of his attempts had failed. 

Bardeen first studied and confirmed that Shockley’s mathematics were correct and that 
his approach was consistent with accepted theory. Shockley’s experiments should work. But 
the results they found using geimanium, a common semiconductor, didn’t match the theory. 

Bardeen guessed that unspecified surface interference on the germanium must be 
blocking the electric current. The three men set about testing the responses of semiconduc- 
tor surfaces to light, heat, cold, liquids, and the deposit of metallic films. On wide lab 

183 



184 Semiconductor Transistor 


benches they tried to force electric current into the germanium through liquid metals and 
then through soldered wire contact points. Most of November and much of December 1947 
were consumed with these tests. 

They found that the contact points worked — sort of. A strong current could be forced 
through the germanium to a metal base on the other side. But rather than amplifying a signal 
(making it stronger), it actually consumed energy (made it weaker). 

Then Bardeen noticed something odd and unexpected. He accidentally misconnected 
his electrical leads, sending a micro-current to the germanium contact point. When a very 
weak current was trickled through from wire solder point to base, it created a “hole” in the 
germanium’s resistance to current flow. A weak current converted the semiconductor into a 
superconductor. 

Bardeen had to repeatedly demonstrate the phenomenon to convince both himself and 
his teammates that his amazing results weren’t fluke occurrences. Time after time the re- 
sults were the same with any semiconductor material they tried: high current, high resis- 
tance; low current, virtually no resistance. 

Bardeen named the phenomenon “transfer resistors,” or transistors. It provided engi- 
neers with a way to both rectify a weak signal and boost it to many times its original 
strength. Transistors required only 1/50 the space of a vacuum tube and 1/1,000,000 the 
power and could outperform vacuum tubes. For this discovery, the three men shared the 
1956 Nobel Prize for Physics. 


Aaseng, Nathan. American Profiles: Twentieth-Century Inventors. New York: Facts 
on File, 1991. 

. The Inventors: Nobel Prizes in Chemistry. Minneapolis, MN: Lemer, 1988. 

Hoddeson, Lillian. True Genius: The Life and Science of John Bardeen. Washington, 
DC: National Academy Press, 2005. 

Olney, Ross. Amazing Transistor: Key to the Computer Age. New York: Simon & 
Schuster Children’s, 1998. 

Phelan, Glen. Flowing Currents: The Quest to Build Tiny Transistors. Washington, 
DC: National Geographic Society, 2006. 

Riordan, Michael. Crystal Fire: The Birth of the Information Age. New York: W. W. 
Norton, 1997. 



Ti Fun Facts: The first transistor radio, the Regency TR-1, hit the market 
/ on October 18, 1954. It cost $49.95 (the equivalent of $361 in 2005 dol- 
' lars!). It wasn’t until the late 1960s that transistor radios became cheap 
enough for everyone to afford one. 


More to Explore 


The Big Bang 

Year of Discovery: 1948 


What Is It? The universe began with the giant explosion of an infinitely dense, 
atom-sized point of matter. 

Who Discovered It? George Gamow 


Why Is This One of the 100 Greatest? 

The study of our history and origins is critical to understanding who we are. That in- 
cludes the history of humans, of life on our planet, of our planet itself, and of the universe as a 
whole. But how can anyone study a history that came and went unseen billions of years ago? 

Gamow’s work represents the first serious attempt to create a scientific, rational de- 
scription of the beginning of our universe. It was Gamow who named that moment of explo- 
sive birth the “Big Bang,” a name still used today. Gamow was able to mathematically 
re-create the conditions of the universe billions of years ago and to describe how those ini- 
tial conditions led to the present universe we can see and measure. His discoveries began 
scientific study of the ancient past. 


How Was It Discovered? 

In 1926 Edwin Hubble discovered that the universe is expanding — growing larger. 
That discovery made scientists wonder what the universe looked like in the past. Has it al- 
ways been expanding? How small did it used to be? Was there some moment when the uni- 
verse began? What did it look like way back then? 

Some began to speculate about when and how the universe began. In 1927 Georges 
Lemaitre proposed that Hubble’s discovery meant that at some distant point in the past, the 
entire universe had been compressed into a single infinitely dense atom of matter. He called 
it the “ cosmic egg.” By 1930 a few scientists had attempted to describe this “cosmic egg” 
and how it exploded to create our universe’s ongoing expansion. 

George Gamow was born in 1904 in Odessa, Ukraine. As a young astronomy student, 
Gamow was known as much for his practical jokes and late-night parties as for his science. 
Still, by 1934 he had immigrated to America and secured a professorship of theoretical 
physics at George Washington University in Washington, DC. It was there that Gamow first 
heard of the cosmic egg concept. The problem with this theory was that there was no sci- 
ence, no data, no numerical studies to back it up. 


185 



186 The Big Bang 


Gamow decided to use available physics, mathematics, and quantum theory tools to 
prove whether the universe began as a single immeasurably dense atom called the cosmic 
egg. He started with Einstein’s equations on general relativity. 

In the 1940s Gamow added his own earlier work, which showed that the sun’s nuclear 
furnace was driven by the conversion of hydrogen nuclei into helium. He used the mathe- 
matics of this model to determine what would happen to various atoms in a primordial fire- 
ball. He used research from the development of the atomic bomb and test data on 
high-energy radiation of various nuclei to describe what happened inside a fire of almost 
infinite temperature. 

From these sources, he slowly built a model of the cosmic egg’s explosion and of the 
chemical reactions that happened in the seconds thereafter. He called that explosion the 
“Big Bang” and mathematically showed how, at that moment, the universe had been com- 
posed primarily of densely packed neutrons. This allowed him to use available studies 
showing how neutrons, under extreme heat and pressure, combine into larger nuclei and 
also separate into protons and electrons, forming hydrogen and helium as they do. 

Gamow was able to mathematically trace this cosmic explosion forward in time. This 
description included a detailed, second-by-second picture of the fireball explosion and 
showed, according to known physics and chemistry laws, how that explosion resulted in the 
composition and distribution of matter that makes up the present universe. 

Gamow also showed that the Big Bang would have created a vast surge of energy that 
spread and cooled as the universe expanded. But this energy would still be “out there” and 
could be detected as a faint “afterglow” or echo of that great explosion. This echo would 
show up as a band of noise at 5°K. 

This cosmic background radiation was finally detected in the late 1990s by advanced 
radio astronomers, which confirmed Gamow ’s Big Bang theory. Using physics, chemistry, 
and math, Gamow had discovered the birth of the universe, 15 billion years ago. 


Alpher, Ralph. Genesis of the Big Bang. New York: Oxford University Press, 2001. 

Barrow, John. The Origin of the Universe. New York: Basic Books, 1994. 

Fox, Karen. The Big Bang: What Is It, Where Does It Come From, and Why It Works. 
New York: John Wiley & Sons, 2002. 

Gribbin, John. In Search of the Big Bang. Fondon: Heinemann, 1986. 

Hawking, Stephen. A Brief History of Time. New York: Bantam Books, 1988. 

Fongair, Malcolm. The Origins of the Universe. New York: Cambridge University 
Press, 1990. 



Ti Fun Facts: Gamow was an imposing figure at six feet, three inches and 
/ over 225 pounds but was known for his impish practical jokes. He was 
' once described as “the only scientist in America with a real sense of hu- 
mor” by a United Press International reporter. 


More to Explore 


More to Explore 187 


Munitz, Milton, ed. Theories of the Universe: From Babylonian Myths to Modern Sci- 
ence. New York: Free Press, 2001. 

Rees, Martin. Before the Beginning: Our Universe and Others. Reading, MA: Addi- 
son-Wesley, 1997. 

Silk, Joseph. The Big Bang, 3d ed. San Francisco: W. H. Freeman, 2001. 

Weinberg, Steven. The First Three Minutes. New York: Basic Books, 1987. 


Definition ol Information 

Year of Discovery: 1948 


What Is It? Information can both follow all mathematical and physical laws 
created to describe matter and act like physical matter. 

Who Discovered It? Claude Shannon 


Why Is This One of the 100 Greatest? 

Every time you surf the Net, download an article, print from your computer screen, use 
a cell phone, rent a DVD, or listen to a CD, you do so because of Claude Shannon’s discov- 
ery. The whole digital revolution started with Claude Shannon’s discovery that information 
can be turned into digital bits (single blocks) of information and treated like any physical 
flow of matter. 

Shannon made information physical. His discovery allowed physicists and engineers 
to switch from analog to digital technologies and opened the door to the Information Age. 
His 1948 article describing the digital nature of information has been called the Magna 
Carta of the Information Age. 

How Was It Discovered? 

Claude Shannon was born in rural Michigan in 1916 and grew up with a knack for 
electronics — turning long fences of barbed wire into his private telephone system, and earn- 
ing money rebuilding radios. He studied for his doctorate in mathematics at the Massachu- 
setts Institute of Technology (MIT). His professors described him as brilliant, but not 
terribly serious as a student, spending his time designing rocket-powered Frisbees and 
juggling machines. 

However, his 1938 master’s thesis (written as part of his studies) startled the world of 
physics. In it Shannon described the perfect match between electronic switching circuits 
and the mathematics of nineteenth-century British genius George Boole. Shannon showed 
that a simple electronic circuit could carry out all of the operations of Boolean symbolic 
logic. This was the first time anyone had showed that more than simple mathematics could 
be embodied in electronic circuits. This student thesis opened the door to digital computers, 
which followed a decade later. 

After graduation Shannon was hired by Bell Telephone Laboratories in New Jersey. 
Engineers there faced a problem: how to stuff more “information” into a noisy wire or mi- 
crowave channel. They gave the job to Claude Shannon, even though he was best known for 
riding a unicycle through the lab hallways. 


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Shannon bypassed others’ attempts to work with specific kinds of information — text, 
numbers, images, sounds, etc. He also decided not to work on any single way of transmit- 
ting information — along a wire, sound waves through the air, radio waves, microwaves, etc. 
Instead, Shannon decided to focus on a question so basic, no one had thought to study it: 
What is information? What happened when information traveled from sender to receiver? 

Shannon’s answer was that information consumed energy and, upon delivery, reduced 
uncertainty. In its simplest form (an atom or a quantum of energy), information answered a 
simple yes/no question. That answer reduced (or eliminated) uncertainty. Flip a coin. Will it 
be heads or tails? You don’t know. You are uncertain. When it lands, you get information: 
yes or no. It was heads or it wasn’t. Uncertainty is gone. That’s information. 

Shannon realized that he could convert all information into a long string of individual 
simple yes/no bits of information and that electrical circuits were ideal for processing and 
transmitting this kind of digital information. In this way, he converted information — in any 
form — into a string of digital yeses and nos: ones and zeros. 

Shannon was then able to apply the laws of physics to information streams. He showed 
that there was a limit to the amount of information that could be pushed through any com- 
munications channel — just as there was a limit to the amount of water that can be pushed 
through a hose no matter how great the pressure. He also derived a mathematical equation to 
describe the relationship between the range of frequencies available to carry information 
and the amount of information that can be carried. This became what we call “bandwidth.” 

Shannon’s discovery made information as physical and easy to work with as water 
flowing through a pipe or air pumped through a turbine. In this way, Shannon discovered 
what information is and opened the door to our modern digital age. 

Fun Facts: There are 6,000 new computer viruses released every month. 

More to Explore 

Adler, Robert. Science Firsts. New York: John Wiley & Sons, 2003. 

Horgan, John. “Claude Shannon: Unicyclist, Juggler, and Father of Information The- 
ory.” Scientific American 262, no. 1 (1995): 22-22B. 

Liversidge, Anthony. “Claude Shannon.” OMNI (August 1997): 61. 

Riordan, Michael. Crystal Fire: The Birth of the Information Ace. New York: W. W. 
Norton, 1997. 

Shannon, Claude. The Mathematical Theory of Communication. Urbana: University 
of Illinois Press, 1999. 

Sloane, N., and Aaron Wyner. Claude Elwood Shannon: Collected Papers. 
Piscataway, NJ: IEEE Press, 1997. 


Jumpin’ Genes 


Year of Discovery: 1950 


What Is It? Genes are not permanently fixed on chromosomes, but can jump 
from position to position. 

Who Discovered It? Barbara McClintock 


Why Is This One of the 100 Greatest? 

Every researcher in the world accepted that genes were strung along chromosomes in 
fixed positions like pearls on a necklace. Working alone in a small, windswept cornfield at 
Cold Springs Harbor, Long Island, Barbara McClintock proved every other genetic scien- 
tist in the world wrong. 

Carefully studying wild corn, Barbara McClintock found that genes not only can 
jump, but regularly do jump from one position to another on a chromosome. She found that 
a few controlling genes direct these jumping messenger genes to shift position and turn on, 
or turn off, the genes next to them in their new location. 

Barbara McClintock’s work became the building block for a dozen major medical and 
disease-fighting breakthroughs. The 1983 Nobel Prize Committee called Barbara 
McClintock’s pioneering work “one of the two great discoveries of our time in genetics.” 


How Was It Discovered? 

With a Ph.D. in genetics, Barbara McClintock lived in a trim two-room apartment over the 
bright-green-painted garage of the Carnegie Institute’s Cold Spring Harbor Research Facility. 

A small, slight woman, Barbara stood barely five feet tall and weighed less than 90 
pounds. Her face and hands were worn and wrinkled from long exposure to wind and sun. 

Cold Spring Harbor is an isolated spot on northeastern Long Island characterized by 
wind, rolling sand dunes, and waving shore grass. Stooping in a small half-acre cornfield 
tucked between the facility’s cluster of buildings and the choppy waters of the Long Island 
Sound, Barbara planted corn seeds by hand one-by-one in carefully laid out rows. 

The year 1950 was Barbara’s sixth year of planting, growing, and studying the genes 
of these corn plants as they passed from generation to generation. She often felt more like a 
farmer than a genetics researcher. 

How Barbara spent her days depended on the season. In summer, most of her time was 
spent in the cornfield, nurturing the plants that would produce her data for the year, weed- 
ing, checking for pests and disease that could ruin her experiments. In the fall she harvested 
each ear by hand, carefully labeled it, and began her lab analysis of each gene’s location and 

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structure on the chromosomes of each ear. Her lab consisted of one powerful microscope, 
chemical lab trays, and stacks of journals to record her findings. This work consumed the 
long hours of winter. 

In the spring she split her time between numerical analysis of the previous year’s data 
and field planning and preparation for the next generation of com plants. 

She carefully tracked color mutations, patterns, and changes year after year and dis- 
covered that genes are not fixed along chromosomes as everyone thought. Genes could 
move. They did move. Some genes seemed able to direct other genes, telling them where to 
go and when to act. These genetic directors controlled the movement and action of other 
genes that jumped positions on command and then turned on — or turned off — the genes 
next to them in their new location. 

It sounded like scientific heresy. It contradicted every genetics textbook, every genet- 
ics research paper, and the best minds and most advanced research equipment on Earth. At 
the end of the 1950 harvest season Barbara debated about releasing her results and finally 
decided to wait for one more year’ s data. 

McClintock presented her research at the 195 1 national symposium on genetic research. 
Her room had seats for 200. Thirty attended. A few more straggled in during her talk. 

She was not asked a single question. Those few left in the room when she finished sim- 
ply stood up and left. 

As so often happens with radically new ideas, Barbara McClintock was simply dis- 
missed by the audience with a bored and indifferent shrug. She was ignored. They couldn’t 
understand the implications of what she said. 

Feeling both helpless and frustrated, Barbara returned to harvest her cornfield and start 
her analysis of the seventh year’ s crop. 

It took another 25 years for the scientific community to understand the importance of 
her discovery. 


Dash, Joan. The Triumph of Discovery. New York: Simon & Shuster, 1991. 

Heiligman, Deborah. Barbara McClintock: Alone in Her Field. New York: W. H. 
Freeman, 1998. 

Keller, Evelyn. A Feeling for the Organism: The Life and Work of Barbara 
McClintock. San Francisco: W. H. Freeman, 1993. 

Maranto, Gina. “At Fong Fast — A Nobel for a Foner.” Discover (December 1983): 26. 

Opfell, Olga. The Lady Laureates: Women Who Have Won the Nobel Prize. Metuchen, 
NJ: Scarecrow Press, 1993. 

Shields, Barbara. Winners: Women and the Nobel Prize. Minneapolis, MN: Dillon 
Press, 1999. 



Fun Facts: Barbara McClintock became the first woman to receive an 
unshared Nobel Prize in Physiology or Medicine. When she died in 1992, 
one of her obituaries suggested that she might well be ranked as the great- 
est figure in biology in the twentieth century. 


More to Explore 


Year of Discovery: 1951 


Fusion 


What Is It? The opposite of fission, fusion fuses two atomic nuclei into one, 
larger atom, releasing tremendous amounts of energy. 

Who Discovered It? Lyman Spitzer 


Why Is This One of the 100 Greatest? 

Fusion energy is the power of the sun. It is a virtually unlimited power source that can 
be created from hydrogen and lithium — common elements in the earth’s crust. Fusion is 
clean, environmentally friendly, and nonpolluting. Fusion was theorized in the late 1910s 
and the 1920s. It was mathematically described in the 1930s. It was finally discovered 
(demonstrated in the lab) in 1951. Fusion’s technology was turned into the hydrogen bomb 
shortly thereafter. 

But fusion has not yet been converted into its promised practical reality. It still works 
only in the lab. If this discovery can be converted into a working reality, it will end energy 
shortages for thousands of years. 


How Was It Discovered? 

Scientists had always thought that the sun produced heat and light by actually burning 
its own matter through normal combustion. In the nineteenth century, a few scientists (most 
notably British Lord Kelvin) argued that the sun could create heat from its own gravita- 
tional collapse — but that such a process could only last for a few million years. 

Einstein’s famous 1905 equation (E = me 2 ) allowed scientists to realize that even tiny 
amounts of matter could be turned into tremendous amounts of energy. In 1919 American 
astronomer Henry Russell described the physics and mathematical processes that would al- 
low the sun to fuse hydrogen atoms into helium atoms and release vast amounts of energy in 
the process. The process was called fusion. This theory of how the sun works was con- 
firmed in 1920 by astronomer Francis Aston’s measurements. 

The theory of fusion existed. But was fusion something that could be practically devel- 
oped on Earth? In 1939 German physicist Hans Bethe described — in mathematical de- 
tail — the theory of how to create a fusion reaction on Earth. But there was a problem. 
Bethe’s equations said that hydrogen atoms had to be raised to a temperature of over 100 
million degrees C (180 million°F) and had to be squeezed into a small space so that the pro- 
tons in hydrogen nuclei would collide and fuse into helium nuclei. There was no known ma- 
terial or force that could accomplish such a feat. 

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Dr. Lyman Spitzer founded the Princeton University Plasma Physics Lab in 1948. He 
soon realized that the only way to contain a fusion reaction was with a high-energy mag- 
netic field. He surrounded a donut-shaped tube that contained hydrogen gas with coils of 
wire to create a magnetic field that kept hydrogen atoms trapped while lasers heated them 
many millions of degrees. 

B ut there was a problem. When he looped thousands of loops of wire down through the 
middle of the donut and up along the outside, it naturally packed the wires more densely on 
the inside of the donut than on the outside. That created a stronger magnetic field on the in- 
side (center) of the donut-shaped tube than on the outside. Hydrogen atoms were pushed to 
the outside and flung at near light speed out of the tube. The fusion generator didn’t work. 

Then Spitzer discovered a marvelous remedy. He twisted the donut containing his hy- 
drogen gas into a figure eight. As hydrogen sped through this looping tube, it spent part of 
each lap near the inside of the figure eight and part near the outside and so was kept from be- 
ing pulled out of the tube by variations in the magnetic field 

In 1951 Spitzer completed work on this first hydrogen plasma fusion generator. He 
called it a stellarator — since it was like creating a star — and fired it for the first time for 
only a small fraction of a second, still not sure that superheated hydrogen plasma wouldn’t 
turn into a hydrogen bomb. 

For one glorious half-second the donut-shaped mass of gas blazed supernova bright, 
like a blinding sun burning at 70 million degrees Fahrenheit. Unimaginably bright and hot, 
the gas became a two-foot diameter, seething, explosively powerful pool of hydrogen 
plasma. Then it faded to dull purple, and, two seconds after it first ignited, turned back to 
black. 

For one flickering moment, Lyman Spitzer had created a new star — almost. More im- 
portant, he had discovered that fusion was possible on Earth. 

Fun Facts: As an alternative energy source, fusion has many advan- 
tages, including worldwide long-term availability of low-cost fuel, no 
IP contribution to acid rain or greenhouse gas emissions, no possibility of a 
runaway chain reaction, by-products that are unusable for weapons, and 
minimum problems of waste disposal. 

More to Explore 

Fowler, T. The Fusion Quest. New York: Johns Hopkins University Press, 1997. 

Heiman, Robin. Fusion: The Search for Endless Energy. London: Cambridge Univer- 
sity Press, 1990. 

Peat, F. Cold Fusion. New York: Contemporary Books, 1999. 

Richardson, Hazel. How to Split the Atom. New York: Franklin Watts, 2001. 


Origins of Life 


Year of Discovery: 1952 


What Is It? The first laboratory re-creation of the process of originally creat- 
ing life on Earth. 

Who Discovered It? Stanley Miller 


Why Is This One of the 100 Greatest? 

One of the greatest mysteries has long been: How did life first form on this planet? 
Theories abound. Bacteria not naturally found on Earth have been found in meteorites re- 
covered in Antarctica. Possibly life here came from some other planet. 

For over a hundred years, the most popular scientific theory has been that DNA mole- 
cules (life) first evolved from amino acids that were somehow spontaneously created in the 
soupy chemical mix of the primordial seas. It was just a theory — albeit a popular one — until 
Stanley Miller re-created the conditions of the early oceans in his lab and showed that 
amino acids could, indeed, form from this chemical soup. 

This was the first laboratory evidence, the first scientific discovery, to support the the- 
ory that life on Earth evolved naturally from inorganic compounds in the oceans. It has been 
a cornerstone of biological sciences ever since. 


How Was It Discovered? 

By 1950 scientists had used a variety of methods to determine that the earth was 4.6 
billion years old. However, the oldest fossil records of even tiny bacterial cells were no 
older than 3.5 billion years. That meant that Earth had spun through space for over a billion 
years as a lifeless planet before life suddenly emerged and spread across the globe. 

How, then, did life start? Most agreed that life had to have emerged from inorganic 
chemicals. While this theory made sense, no one was sure if it could really have happened. 

Through the late 1940s Harold Urey, a chemist at the University of Chicago, teamed 
with astronomers and cosmologists to try to determine what Earth’s early environment 
looked like. They determined that Earth’s early atmosphere would chemically resemble the 
rest of the universe — 90 percent hydrogen, 9 percent helium, with the final 1 percent made 
up of oxygen, carbon, nitrogen, neon, sulfur, silicon, iron, and argon. Of these helium, ar- 
gon, and neon don’t react with other elements to form compounds. 

Through experiments, Urey determined that the remaining elements, in their likely 
composition in Earth’s early atmosphere, would have combined to form water, methane, 
ammonia, and hydrogen sulfide. 


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Enter Stanley Miller. In 1952 this 32-year-old chemist decided to test the prevailing 
theory and see if life could be produced from Urey’s mix of chemical compounds. Miller 
carefully sterilized long sections of glass tubing, flasks, and beakers. He built what 
looked like a sprawling erector set of support poles in his lab and clamped flasks, beakers, 
and connecting glass tubes to this structure. He filled one large beaker with sterilized wa- 
ter. He filled other flasks with the three gasses Urey had identified as part of Earth’s early 
atmosphere — methane, ammonia, and hydrogen sulfide. 

Miller slowly boiled the beaker of water so that water vapor would rise into his en- 
closed “atmosphere” of a labyrinth of glass tubes and beakers. There it mixed with the three 
other gasses in swirling clouds in a beaker labeled “atmosphere.” 

Miller realized he needed an energy source to start his life-creating chemical reaction. 
Since other scientists had determined that the early atmosphere contained almost continual 
rolling thunder and lightning storms, Miller decided to create artificial lightning in his at- 
mosphere. He hooked a battery to two electrodes and zapped lightning bolts across the “at- 
mosphere” chamber. A glass pipe led from this chamber and past a cooling coil. Here water 
vapor recondensed and dripped into a collection beaker that was connected to the original 
water beaker. 

After one week of continual operation of his closed-cycle atmosphere, Miller analyzed 
the residue of compounds that had settled in the collection beaker of his system. He found 
that 15 percent of the carbon in his system had now formed into organic compounds. Two 
percent had formed actual amino acids (the building blocks of proteins and of DNA). In just 
one short week. Miller had created the building blocks of organic life! Virtually all scien- 
tists were amazed at how easy it was for Miller to create amino acids — the building blocks 


In 1953 the structure of the DNA molecule was finally discovered. Its structure fit well 
with how Miller’ s amino acid molecules would most likely combine to create longer chains 
of life. This was another bit of evidence to support the idea that Stanley Miller had discov- 
ered of how life on Earth began. 


Davies, Paul. Fifth Miracle: The Search for the Origin and Meaning of Life. New 
York: Simon & Schuster, 2000. 

Gallant, Roy. The Origins of Life. New York: Benchmark Books, 2000. 

Jenkins, Steve. Life on Earth: the Story of Evolution. New York: Houghton Mifflin, 


MacDougall, J. D. Short History of Planet Earth: Mountains, Mammals, Fire, and Ice. 
New York: John Wiley & Sons, 1998. 

Morgan, Jennifer. From Lava to Life: The Universe Tells Our Earth Story. Nevada 
City, CA: Dawn Publications, 2003. 


of life. 



Fun Facts: There are 20 types of amino acids. Eight are “essential amino 
/ acids” that the human body cannot make and must therefore obtain from 
' food. 


More to Explore 


2002 . 


Year of Discovery: 1953 


DNA 


What Is It? The molecular structure of, and shape of, the molecule that carries 
the genetic information for every living organism. 

Who Discovered It? Francis Crick and James Watson 


Why Is This One of the 100 Greatest? 

British biochemist Francis Crick, and his American partner, James Watson, created the 
first accurate model of the molecular structure of deoxyribonucleic acid, or DNA, the mas- 
ter code to the building and operation of all living organisms. That discovery has been 
called by many “the most significant discovery of the century.” 

This discovery of the details of the DNA molecule’s structure allowed medical scien- 
tists to understand, and to develop cures for, many deadly diseases. Millions of lives have 
been saved. Now DNA evidence is commonly used in court. This discovery has also led to 
the unraveling of the human genome and promises to lead to cures for a wide variety of 
other serious aliments and birth defects. 

Crick’s discoveries relating to DNA structure and function reshaped the study of ge- 
netics, virtually created the field of molecular biology, and gave new direction to a host of 
endeavors in various fields of medicine. 

How Was It Discovered? 

The room looked like a tinker toy party gone berserk, like the playroom of overactive 
second-grade boys. Complex mobiles of wire, colored beads, strips of sheet metal, card- 
board cutouts, wooden dowels, and wooden balls dangled from the ceiling like a forest of 
psychedelic stalactites. Construction supplies, scissors, and tin snips were strewn about the 
desks and floor, as were pages of complex equations, stacks of scientific papers, and photo- 
graphic sheets of fuzzy X-ray crystallography images. 

The room was really the second-floor office shared by graduate students Francis Crick 
and James Watson in a 300-year-old building on the campus of Cambridge University. The 
year was 1953. The mobiles were not the idle toys of students with too much free time. 
Rather, they were a frantic effort to win the worldwide race to unravel the very core of life 
and decipher the shape of the DNA molecule. 

By 1950 biochemists had already deduced that DNA in a cell’s nucleus earned genetic 
information. The key mystery was how the huge DNA molecule reproduces itself to physi- 


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cally pass this information to a new cell, a new organism, and a new generation. To answer 
that question, someone had to first figure out what this giant DNA molecule looked like. 

At Cambridge, Crick teamed with American biologist James Watson. The two agreed 
to pool their efforts to construct a model of the DNA molecule while they pursued their sep- 
arate studies and thesis research. 

By 1951 bits and pieces of information about the DNA molecule were emerging from 
across the globe. Erwin Chargaff discovered that a definite ratio of nucleotide sequences 
could be detected in the DNA bases, suggesting a paired relationship. Oswald Avery con- 
ducted experiments on bacteria DNA showing that DNA carried genetic information. Linus 
Pauling conceptualized the alpha helix configuration for certain chains of proteins. 

Crick and Watson attempted to combine these separate clues into a single physical 
structure. Using bits of wire, colored beads, sheet metal, and cardboard cutouts, Crick and 
Watson hung possible spiral models across their shared office. They correctly surmised that 
a linking chain of sugar and phosphate formed the backbone of the DNA spiral. They cor- 
rectly linked base pairs of peptides. Still the model did not fit with available atomic data. 

Also at Cambridge, but independent of Crick and Watson’s efforts, Rosalind Franklin 
used X-ray crystallography to create two-dimensional images of the DNA molecule. In 
mid-January 1953, Rosalind had redesigned the X-ray cameras she used. X-ray film from 
these cameras showed the now-famous “X” shape that suggested a helix shape for the DNA 
molecule. 

Tipped off that Fran kl in had new information, Crick stole one of Rosalind’s X-shaped 
X-rays. This stolen insight finally put Crick and Watson ahead in the race to solve the struc- 
ture of DNA. By mid-February they had constructed the first complete physical model of a 
DNA molecule, using the now-familiar double helix shape, like two intertwined spiral 
chains. 


/g~y\ Fun Facts: If you straightened each strand of DNA from each cell in 
\L / your body and lined them end-to-end, you’d have about nine million ki- 
ll lometers of DNA. That’s enough to reach to the moon and back 13 times! 

More to Explore 

Crick, Francis. Life Itself: Its Origins and Nature. New York: Simon & Schuster, 
1981. 

. Of Molecules and Men. Washington, DC: Washington University Press, 

1966. 

Judson, Horace. The Eighth Day of Creation: Makers of the Revolution in Biology. 
London: S & S Trade Books, 1999. 

Maitland, Edey, and Donald Johanson. BLUEPRINTS: Solving the Mystery of Evolu- 
tion. New York: Penguin Books, 1996. 

More, Ruth. The Coil of Life: The Story of the Great Discoveries of the Life Sciences. 
New York: Knopf, 1991. 


198 DNA 


Olby, Robert. The Path to the Double Helix. Seattle: University of Washington Press, 
1994. 

Sayre, Anne. Rosalind Franklin and DNA. New York: Norton, 1991. 

Stille, Darlene R. Extraordinary Women Scientists. Chicago: Children’s Press, 1995. 

Ulf, Lagerkvist. DNA Pioneers and Their Legacy. New Haven, CT: Yale University 
Press, 1998. 

Watson, James. The Double Helix: A Personal Accoun t of the Discovery of the Struc- 
ture of DNA. New York: Atheneum, 1985. 


Seafloor Spreading 


Year of Discovery: 1957 


What Is It? The ocean floors slowly move, spreading from central rifts, and 
carry the continents on their backs as they do. 

Who Discovered It? Harry Hess 


Why Is This One of the 100 Greatest? 

We now know that Earth’s continents move. Over hundreds of millions of years, they 
drift across Earth’s surface. You have likely seen pictures of what Earth looked like 500 
million years ago. But just 60 years ago, no one believed that it was possible for massive 
continents to move. There was no force great enough to move vast continents weighing tril- 
lions of tons. 

Then Harry Hess discovered the theory of ocean-floor spreading. That discovery sud- 
denly not only made continental movement plausible, but made drifting continents a fact. 
Hess’s discovery was the key evidence that confirmed early theories on continental drift by 
Wegener. Hess’s work launched the study of plate tectonics and created new understanding 
of the history and mechanics of Earth’s crust and started the serious study of the past motion 
of Earth’s continents. 


How Was It Discovered? 

Standing on the bridge of a mammoth deep-ocean drilling ship in the mid- Atlantic in 
1957, Navy Commander Harry Hess watched as a crane operator maneuvered the drilling 
pipe sections from atop the drilling derrick mounted high above the deck. This was the first 
time a ship had been able to drill and collect core samples from the ocean floor 13,000 feet 
below. Hess had designed and managed the operation. He should have been pleased and 
proud. But test after test showed the ocean bottom below them was less than 50 million 
years old — disproving every theory about the ocean floor that Harry Hess had created and 
promoted. 

A geology professor before he joined the navy, Hess had been given command of the 
transport U.S.S. Cape Johnson operating in the Pacific in 1945. Using Navy sonar systems, 
Hess made the first systematic echo-sounding surveys of the Pacific Ocean floor over a 
two-year period as he steamed back and forth on navy assignments. He discovered over 100 
submerged, flat-topped seamounts 3,000 to 6,000 feet under water between the Hawaiian 
and Mariana islands. Hess described these seamounts as “drowned ancient islands” and 
named them guyots (to honor Arnold Guyot, a geology professor at Princeton). 

199 



200 Seafloor Spreading 


Hess theorized that guyots had originally been islands dating back to 800 million years 
ago, a period before coral existed. His argument rested, in part, on his hypothesis that con- 
tinual deposits of sediment on the seafloor had made the sea level rise. 

When, in 1956, fossils only 100 million years old were found in guyots, Hess changed 
his theory to say that guyots had originally been volcanoes that had eroded to flat tops by 
wave action. He abandoned this theory when erosion rate calculations showed that the 
guyots couldn’t have eroded enough to reach their current depth. 

Then his 1957 oceanic core samples showed that the Atlantic Ocean floor was much 
younger than the continents and that oceanic sedimentation rates were slower than previ- 
ously thought. Hess — again — had to search for a new theory. 

Luckily, his 1957 survey allowed him to collect core samples from more than 20 sites 
across the Atlantic. These tests showed that the age of the ocean bottom grew progressively 
older as it moved away from the mid-oceanic ridge and toward either continent. 

The seafloor wasn’t fixed and motionless as everyone had thought. It had to be spread- 
ing, moving as if on a giant conveyor belt, inching year by year away from the mid-oceanic 
ridge. Hess argued that magma rose from the earth’s mantle up through oceanic rifts and 
spread out laterally across the ocean floor. As the magma cooled, it formed new oceanic 
crust. He estimated the oceanic crust to be spreading apart along the mid-oceanic ridge by 
one to two inches a year. 

Hess’s discovery became known as seafloor spreading and was the foundation of the 
plate tectonics revolution in the late 1960s and early 1970s. 

/f~V Fun Facts: The Pacific Ocean is slowly shrinking as the Americas slide 
west. Two hundred million years ago, the Atlantic Ocean didn’t exist. 

H South America and Africa were joined, as were North America and Eu- 
rope. The Atlantic is still spreading and growing. So is the Red Sea. In 
150 million years, that currently skinny sea will be as wide as the Atlantic 
is now. 


More to Explore 

Bermen, Howard, ed. The National Cyclopedia of American Biography, Volume N-63. 
Clifton, NJ: James T. White & Co., 1984. 

Daintith, John, ed. Biographical Encyclopedia of Science. 2d ed. Philadelphia: Norton 
Scientific, 1994. 

Gillispie, Charles Coulston, ed. Dictionary of Scientific Biography. New York: 
Charles Scribner’s Sons, 1998. 

Hess, Harry. “History of the Ocean Basins.” In Petrological Studies, edited by A. 
Engle and H. James. New York: Harper, 1992. 

Rubey, William. “Harry Hammond Hess.” In Yearbook of the American Philosophical 
Society (1995). New York: American Philosophical Society, 1996. 


The Nature of the 
Atmosphere 


Year of Discovery: 1960 


What Is It? The atmosphere is chaotic and unpredictable. 
Who Discovered It? Ed Lorenz 


Why Is This One of the 100 Greatest? 

Ed Lorenz uncovered a nonlinear, complex, interdependent system of equations that 
describe the real movement of the atmosphere. He showed that atmospheric models are so 
dependent on initial and boundary conditions (starting data supplied to the model) that even 
seemingly infinitesimal changes in them create major changes in the system. In other 
words, when a butterfly flaps its wings over Beijing, the models might well predict that it 
will change the weather in New York. But everyone admitted that just couldn’t happen. 

Lorenz discovered not how to make long-range predictions, but rather the forces that 
make such predictions impossible. He then developed chaos theory — the study of chaotic 
and unpredictable systems. Scientists are discovering that many natural, biological, and en- 
vironmental systems are best described and better understood under chaos theory than 
through traditional forms of analysis. 


How Was It Discovered? 

Having a computer was enough of a novelty in 1958 to entice many MIT faculty and 
students to make the trip to Ed Lorenz’s office just to watch the thing work. But excitement 
quickly turned to despair for Lorenz. 

Lorenz created a set of equations to act as a mathematical model of atmospheric storm 
movement and behavior. He noticed that tiny changes in the starting conditions of the 
model soon produced enormous changes in the outcome. Tiny starting differences always 
amplified over time, rather than damping, or normalizing out. 

If the actual atmosphere acted like Lorenz’ s models, he had just proved that long-range 
weather forecasting was impossible since starting conditions were never known with 
enough precision to prevent chaotic, amplified error. It was an unsettling and sinking feel- 
ing to trade the excitement of finding a new research tool for the despair of proving that your 
field and work were both inherently flawed and impossible. 


201 



202 The Nature of the Atmosphere 


When Ed entered Dartmouth College in 1934, he had long ago made up his mind to be 
a mathematician. He graduated with a bachelor’s degree in mathematics in 1938 and en- 
tered Harvard to continue his study of math. With the outbreak of World War II, Lorenz 
joined the Army Air Corps, who assigned him to attend army meteorology classes at MIT. 

He learned to regard the weather as a combination of density, pressure, temperature, 
three-dimensional wind velocities, and the atmosphere’s gaseous, liquid, and solid content. 
The equations that describe this host of variables define the current weather conditions. The 
rates of change in these equations define the changing weather pattern. 

What Lorenz was not taught, and only much later discovered, was that no one knew 
how to use these nonlinear dynamic meteorology equations to actually predict weather and 
that most thought it could not be done. The equations were too complex and required too 
much initial and boundary data. 

Lorenz tried to apply the dynamic equations to predict the motion of storms. As com- 
puters were not commonly available in the early 1950s, most of this work was carried out 
on blackboards and with slide rules and paper and pencil. Each calculation was tediously 
time-consuming. Lorenz was never able to reach any meaningful results while hand- 
calculating these equations. 

In 1958 Lorenz obtained that Royal-McBee LGP-30 computer (about the size of a 
large desk) to develop his sets of dynamic, nonlinear model equations. The results of those 
computer simulations showed that tiny initial differences amplified over time, rather than 
gradually normalizing out. If the model was right, weather was chaotic and inherently 
unpredictable. 

Several years of atmospheric testing convinced Lorenz and others in his department 
that he and his model were correct. The atmosphere was a chaotic rather than a predictable 
system (such as the system of interactions between inorganic chemicals, or the physical pull 
of gravity). A drive to use a new tool to complete an old project had turned into one of the 
most profound discoveries for the science of meteorology. 

Lorenz will always be known as the person who discovered the true nature of the atmo- 
sphere and who thereby discovered the limits of accuracy of weather forecasting. 

(f~f\ Fun Facts: Actor Jeff Goldblum played the role of Ian Malcolm in the 
V Jurassic Park movies. Malcolm is a mathematician who specializes in 
U the study of the chaos theory and refers to himself as a “chaotician.” A 
central theme of these movies is proving that Malcolm’s chaos theories 
are right. 


More to Explore 

Luller, John. Thor’s Legions. Boston: American Meteorological Society, 1990. 

Gleick, James. Chaos: Making a New Science. New York: Viking, 1991. 

Lorenz, Ed. The Essence of Chaos. Seattle: University of Washington Press, 1993. 

. “A Scientist by Choice.” In Proceedings of the Kyoto Prize for 1991. Kyoto, 

Japan: The Inamori Loundation, 1991. 

Parker, Berry. Chaos in the Cosmos. New York: Plenum Press, 1996. 


Year of Discovery: 1962 


Quarks 


What Is It? Subatomic particles that make up protons and neutrons. 
Who Discovered It? Murry Gell-Mann 


Why Is This One of the 100 Greatest? 

First scientists identified plant fibers, then individual cells. Then scientists conceived of 
atoms and molecules. In the early twentieth century, scientists discovered electrons and then 
the existence of protons and neutrons. In each case, scientists believed that they had finally 
discovered the smallest possible particle of matter. Each time this belief proved wrong. 

The discovery of quarks (fundamental particles that make up protons and neutrons) in 
1962 led science into the bizarre and alien quantum world inside protons and neutrons, a 
world of mass with no mass and where mass and energy are freely exchanged. This discovery 
has taken science one giant step closer to answering one of the most basic questions of all: 
What really is matter made of? At each new level the answer and the world grows stranger. 


How Was It Discovered? 

As the nineteenth century closed, Marie Curie broke open the atom and proved that it 
was not the smallest possible particle of matter. Soon scientists had identified two sub- 
atomic particles: electrons and protons. In 1932 James Chadwick discovered the neutron. 
Once again scientists thought they had uncovered the smallest particles of all matter. 

When particle accelerators were invented in the mid- 1930s, scientists could smash 
neutrons into protons, and protons into heavier nuclei to see what the collisions would pro- 
duce. In the 1950s Donald Glaser invented the “bubble chamber.” Subatomic particles were 
accelerated to near light speed and flung into this low-pressure, hydrogen-gas-filled cham- 
ber. When these particles struck a proton (a hydrogen nucleus), the proton disintegrated into 
a host of strange new particles. Each of these particles left a telltale trail of infinitesimally 
small bubbles as they sped away from the collision site. Scientists couldn’t see the particles 
themselves. But they could see the trails of bubbles. 

Scientists were both amazed and baffled by the variety and number of these tiny tracks 
on bubble chamber plots (each indicating the temporary existence of a previously unknown 
particle). They were unable to even guess at what these new subatomic particles were. 

Murry Gell-Mann was born in Manhattan in 1929. A true prodigy, he could multiply 
large numbers in his head at age three. At seven, he beat twelve- year-olds in spelling bees. 
By age eight, his intellectual ability matched that of most college students. Gell-Mann, 

203 



204 Quarks 


however, was bored and restless in school and suffered from acute writer’s block. He rarely 


finished papers and project descriptions, even though they were easy for him to complete. 

Still, he sailed through undergraduate school at Yale and then drifted through MIT, the 
University of Chicago (where he worked for Fermi) and Princeton (where he worked for 
Oppenheimer). By the age of 24, he had decided to focus on understanding the bizarre parti- 
cles that showed up on bubble chamber plots. Bubble chamber plots allowed scientists to 
estimate the size, electrical charge, direction, and speed of each particle, but not its specific 
identity. By 1958 almost 100 names were in use to identify and describe this forest of new 
particles that had been detected. 

Gell-Mann decided that he could make sense of these particles if he applied a few fun- 
damental concepts of nature. He assumed that nature was simple and symmetrical. He also 
assumed that, like all other matter and forces in nature, these subproton sized particles had 
to be conservative. (Mass, energy, and electrical charge would be conserved — not lost — in 
all collision reactions.) 

With these principles as his guides, Gell-Mann began to group and to simplify the re- 
actions that happened when a proton split apart. He created a new measure that he called 
strangeness that he took from quantum physics. Strangeness measured the quantum state of 
each particle. Again he assumed that strangeness would be conserved in each reaction. 

Gell-Mann found that he could build simple patterns of reactions as particles split apart 
or combined. However, several of these patterns didn’t appear to follow the laws of conser- 
vation. Then Gell-Mann realized that he could make all of the reactions follow simple, con- 
servative laws if protons and neutrons weren’t solid things, but were, instead, built of three 
smaller particles. 

Over the course of two years’ work, Gell-Mann showed that these smaller particles 
had to exist inside protons and neutrons. He named them k-works, then kworks for short. 
Soon afterward he read a line by James Joyce that mentioned “three quarks.” Gell-Mann 
changed the name of his new particles to quarks. 


Apfel, Necia. It’s All Elementary: From Atoms to the Quantum World of Quarks, Lep- 
tons, and Gluons. New York: HarperColllins, 1997. 

Berger, Melvin. Atoms, Molecules and Quarks. New York: Penguin Young Readers’ 
Group, 1996. 

Bortz, Fred. Quarks. Cherry Hill, NJ: Rosen Publishing, 2004. 

Gell-Mann, Murry. The Quark and the Jaguar. New York: Abacus Books, 1995. 

Kidd, Jerry. Nuclear Power: The Study of Quarks and Sparks. New York: Facts on 
File, 2006. 

Schwartz, David. Q Is for Quark: A Science Alphabet Book. Berkeley, CA: Ten Speed 
Press, 2001. 



Ti Fun Facts: The James Joyce line mentioned above is “Three quarks for 
J Muster Mark!” in Finnegan’s Wake. Can you find that quote? 


More to Explore 


Quasars and Pulsars 


Years of Discovery: 1963 and 1967 


What Is It? The discovery of super-dense, distant objects in space. 

Who Discovered It? Allan Rex Sandage (quasar) and Antony Hewish and 
Jocelyn Bell (pulsar) 


Why Is This One of the 100 Greatest? 

Quasars and pulsars represent a new class of objects in space, a new kind of massive, 
extraordinarily bright object. Massive, exceedingly dense, and producing powerful radio 
and light transmissions, quasars and pulsars radically expanded and altered scientists’ view 
of space and space structures. 

Quasars are some of the brightest and most distant objects in the universe. Pulsars pro- 
vide hints of the life path and life expectancy of stars. Their discovery led to a greater under- 
standing of the life and death of stars and opened up new fields of study in astronomy, 
super-dense matter, gravitation, and super-strong magnetic fields. 


How Was It Discovered? 

In the fall of 1960, American astronomer Allan Rex Sandage noticed a series of dim 
objects that looked like stars. He cross checked them with a radio telescope to see if they 
transmitted radio signals as well as dim light. 

Each of these dim objects produced amazingly powerful radio signals. No known ob- 
ject could do that. Maybe they weren’t really stars — at least not stars like other stars. 
Sandage called these mystery objects quasi-stellar radio sources. Quasi-stellar quickly 
shortened to quasar. 

Sandage studied the spectrographic lines of these strange objects (lines that identify 
the chemical makeup of a distant star). The lines didn’t match any known chemical ele- 
ments and could not be identified. 

Sandage and Dutch-born American astronomer Maarten Schmidt finally realized that 
the spectral lines could be identified as normal and common elements //they were viewed as 
spectrograph lines that normally occurred in the ultraviolet range and had been displaced by 
a tremendous red shift (Doppler shift) into the visible range. (Doppler shifts are changes in 
the frequency of light or sound caused by the motion of an object.) 

While that explanation solved one mystery, it introduced another. What could cause 
such a giant Doppler shift? In 1963 they decided that the only plausible answer was distance 


205 



206 Quasars and Pulsars 


and that the quasars must be over a billion light years away — the most distant objects ever 
detected! 

But now the dim light of the quasars was too bright for a single star at that distance 
— often 1,000 times as bright as whole galaxies. Sandage and Schmidt proposed that each 
quasar must really be a distant galaxy. However, the measured radio signals varied too 
much (on the order of days and hours) to be a galaxy of separate stars. That indicated a com- 
pact mass, not a galaxy. 

Quasars remained a perplexing mystery until, in 1967, it was proposed that they were 
really the material surrounding massive black holes. Quasars instantly became the most in- 
teresting and important objects in distant space. 

That same year (in July 1967) Cambridge University Astronomy professor Antony 
Hewish completed a 4.5-acre radio antenna field to detect radio frequency transmissions 
from the farthest corners of space. This gargantuan maze of wire would be the most sensi- 
tive radio frequency receiver on Earth. 

The radio telescope printed 100 feet of output chart paper each day. Graduate assistant 
Jocelyn Bell had the job of analyzing this chart paper. She compared the chart’s squiggly 
lines to the position of known space objects and then compared the known electromagnetic 
emissions of these bodies to the chart’s squiggles and spikes in order to account for each 
mark on the chart. 

Two months after the telescope started up. Bell noticed an unusual, tight-packed pat- 
tern of lines that she called a “bit of scruff’ — a squiggling pattern she couldn’t explain. She 
marked it with a question mark and moved on. 

Four nights later, she saw the same pattern. One month later she found the same pattern 
of scruff and recognized that the antenna was focused on the same small slice of sky. She 
took the extra time to expand and measure the squiggles. Whatever it was, this radio signal 
regularly pulsed every 1 1/3 seconds. No natural body in the known universe emitted regu- 
lar signals like that. 

Before Hewish publicly announced their discovery, Bell found another bit of scruff on 
chart printouts from a different part of the sky. The pulses of this second signal came 1.2 
seconds apart and at almost the exact same frequency. 

Every theoretician at Cambridge was brought in to explain Jocelyn’s scruff. After 
months of study and calculation the science team concluded that Bell had discovered 
super-dense, rotating stars. Astronomers had mathematically theorized that when a huge 
star runs out of nuclear fuel, all matter in the star collapsed inward, creating a gigantic 
explosion, called a supernova. 

What remained became a hundred million times denser than ordinary matter — a neu- 
tron star. If the star rotated, its magnetic and electric fields would broadcast beams of pow- 
erful radio waves. From Earth, a rapidly rotating neutron star would appear to pulse and so 
these were named “pulsars.” 



Fun Facts: The more distant the quasar is, the redder its light appears on 
Earth. The light from the most distant quasar known takes 13 billion 
light-years to reach Earth. Thirteen billion light-years is how far away 
that quasar was 1 3 billion years ago when the light we now see first left 
the star and headed toward where Earth is now. Quasars are the most dis- 
tant objects in the universe. 


More to Explore 207 


More to Explore 

Asimov, Isaac. Black Holes, Pulsars, and Quasars. New York: Gareth Stevens, 2003. 

McGrayne, Sharon. Nobel Prize Women in Science: Their Lives, Struggles, and Mo- 
mentous Discoveries. New York: Carol Publishing Group, A Birch Lane Press 
Book, 1993. 

Raymo, Chet. 365 Starry Nights: An Introduction to Astronomy for Every Night of the 
Year. New York: Simon & Schuster, 1992. 

Schaaf, Fred. The Amateur Astronomer: Explorations and Investigations. New York: 
Franklin Watts, 1994. 

Stille, Darlene R. Extraordinary Women Scientists. Chicago: Children’s Press, 1995. 


Complete Evolution 

Year of Discovery: 1967 


What Is It? Evolution is driven by symbiotic mergers between cooperating 
species. 

Who Discovered It? Lynn Margulis 


Why Is This One of the 100 Greatest? 

Charles Darwin was the first to conceive that species evolved — changed — over time, 
and the first to identify a driving force for that change — survival of the fittest. Darwin’s the- 
ories instantly became the bedrock of biological thinking and survived unchallenged for a 
century. 

Lynn Margulis was the first to discover and prove modification to Darwin’s theory of 
evolution. In so doing, she filled in the one, nagging gap in Darwin’s theory. More than any 
scientist since Darwin, she has forced a radical revision of evolutionary thinking. Like Co- 
pernicus, Galileo, Newton, and Darwin before her, Margulis has uprooted and changed 
some of science’s most deeply held theorems and assumptions. 


How Was It Discovered? 

Born in 1938, Lynn Margulis was raised on the streets of Chicago. Called precocious 
as a child, she entered the University of Chicago when only 14 years old. There she studied 
genetics and evolution. 

Since Darwin’s time the field of evolution has struggled with a problem called “varia- 
tion.” Researchers assumed that variation in an individual’s DNA provided the “trial bal- 
loons” that natural selection kept or discarded. Those mutations that nature kept would 
slowly spread through the entire species. 

However, a nagging question could not be answered: What causes new variations in 
the individuals of a species? Theories centered on random errors that somehow rewrote sec- 
tions of the DNA genetic code. 

Even early in her career, it seemed obvious to Margulis that this was not what really 
happened. Margulis saw no hard evidence to support small, random mutations driving spe- 
cies evolution. Instead she found evidence for large, sudden jumps — as if evolution hap- 
pened not as a slow, steady creep, but as sudden, dramatic adaptive advances. She saw that 
evolutionary change was not nearly so random as others believed. 

Margulis focused on the concept of symbiosis — two organisms (or species) living co- 
operatively together for their mutual benefit. She found many elementary examples of two 

208 



More to Explore 209 


species choosing to live in intimate, interdependent existence. Lichens were composed of 
an algae and a fungus that, living as a single organism, survived better than either could 
alone. Cellulose-digesting bacteria lived in the gut of termites. Neither could survive with- 
out the other. Yet together they both thrived. Without a symbiotic merger, this arrangement 
could never have developed. 

Margulis found symbiotic relationships abounding wherever she looked. Existing spe- 
cies sought out new cooperative, symbiotic relationships to improve their survivability. Hu- 
man corporations did it. So did nature when, for example, a bacterium (a highly evolved life 
form) incorporated itself into another existing species to create a new symbiotic mutation 
and the species jumped forward in its capabilities. 

Margulis studied Earth’s early life forms and discovered four key symbioses that al- 
lowed the development of complex life on Earth: (1) a union between a heat-loving 
archae-bacterium and a swimming bacterium (a spirochete). Some of the original spiro- 
chete genes were then coopted (2) to produce the organizing centers and filaments that pull 
genetic material to opposite sides of a cell before it splits. This allowed the creation of com- 
plex life forms. This new creature engulfed (3) an oxygen-burning bacterium (once oxygen 
began to proliferate in the atmosphere). Finally, this swimming, complex, oxygen-process- 
ing one-celled organism engulfed (4) a photosynthesizing bacterium. The result of this 
four-step evolutionary merger was all modem algae and plants! 

Margulis showed that the cells of plants, animals, fungi, and even humans evolved 
through specific series of symbiotic mergers that represented large, instant steps forward 
for the involved species. 

She published her landmark work in 1967, but biologists were skeptical until it was 
shown that mitochondria in all human cells have their own DNA, thus establishing that even 
human cells are the result of at least one symbiotic merger. This discovery spurred a genera- 
tion of scientists who have searched for, found, and studied symbiotic mergers. They have 
found them everywhere. 

Nine out of ten plants survive because of symbiotic mergers with root fungi that pro- 
cess crucial nutrients from the soil. Humans and other animals have whole colonies of coop- 
erating bacteria and other bugs living in our guts to process and digest the food we eat. 
Without them, we would not survive. Without Margulis’s discovery, Darwin’s theory 
would have remained incomplete. 


Adler, Robert. Science Firsts. New York: John Wiley & Sons, 2002. 

Brockman, John. Curious Minds: How a Child Becomes a Scientist. New York: 
Knopf, 2005. 

Margulis, Lynn. Diversity of Life: The Five Kingdoms. Hillside, NJ: Enslow Publish- 



Fun Facts: Margulis and her writer/astronomer husband, Carl Sagan, are 
J the ones who said: “Life did not take over the globe by combat, but by 
I networking (cooperation), and Darwin’s notion of evolution driven by 
the combat of natural selection is incomplete.” 


More to Explore 


ers, 1996. 


210 Complete Evolution 


. Microcosmos: Four Billion Years of Evolution from Our Microbial Ances- 
tors. Berkeley: University of California Press, 1997. 

. Symbiotic Planet: A New Look at Evolution. New York: Basic Books, 1998. 

. What Is Life? Berkeley: University of California Press, 2000. 

Sapp, Jan. Evolution by Association: A History of Symbiosis. New York: Oxford Uni- 
versity Press, 1999. 


Dark Matter 


Year of Discovery: 1970 


What Is It? Matter in the universe that gives off no light or other detectible 
radiation. 

Who Discovered It? Vera Rubin 


Why Is This One of the 100 Greatest? 

Calculations of the expansion of the universe didn’t work. Calculations of the speed of 
stars in distant galaxies didn’t match what astronomers observed. Calculations of the age of 
the universe (based on the speed of its expansion) didn’t make sense. Something had to be 
wrong with the methods used for these calculations. With these major question marks hang- 
ing over the calculations, no one could dependably calculate the history of, present mass of, 
or future of, the universe. Much of physics research ground to a halt. 

Vera Rubin only meant to test a new piece of equipment. What she discovered was that 
the actual motion of stars and galaxies appeared to prove that Newton’s laws — the most 
fundamental principles of all of astronomy — were wrong. In trying to explain the difference 
between observations and Newtonian physics, Rubin discovered dark matter — matter that 
exists but gives off no light or other radiation that scientists could detect. Astronomers and 
physicists now believe that 90 percent of the mass of the universe is dark matter. 


How Was It Discovered? 

In 1970 Vera Rubin worked at the Department of Terrestrial Magnetism (DTM) at the Car- 
negie Institute of Washington. DTM’s director, astronomer Kent Ford, had just created a new 
high-speed, wide-band spectrograph that could complete eight to ten spectrographs (graphic im- 
ages on chart paper of some spectrum — in this case of the energy emitted from distant stars at dif- 
ferent frequencies along the frequency spectrum) in a single night while existing models were 
lucky to complete one in a day. Vera was itching to see what Ford’s invention could do. 

During the night of March 27, 1970, Rubin focused the DTM telescope on 
Andromeda, the nearest galaxy to our own. She planned to see whether Andromeda’s mil- 
lions of stars really moved as existing theory said they should. 

When attached to powerful telescopes, spectrographs detect the presence of different 
elements in a distant star and display what they detect on chart paper. Rubin rigged a 
high-power microscope to read the charts created by Ford’s spectrograph. 

Rubin knew that the marks astronomers measured on a spectrograph shift a tiny bit 
higher or lower on the frequency chart paper depending on whether the star is moving to- 

211 



212 Dark Matter 


ward Earth or away from it. This frequency shift is called a Doppler shift. The same kind of 
shift happens with sound waves as a car passes and the sound of its engine seems to change 
to a lower frequency. The greater that shift, the greater the object’s speed. Rubin wanted to 
see if she could use Doppler shifts and Kent’s new spectrograph to measure the speed of 
stars in distant galaxies. 

She found that the stars near the outer edge of Andromeda moved just as fast as the 
stars near the galaxy’s center. That wasn’t the way it was supposed to be. 

Over a period of two months she completed 200 spectrographs. For every galaxy it was 
the same. The velocities of stars she measured were all wrong. According to every known 
law of physics, some of those stars were moving too fast for gravity to hold them in their 
galaxies, and they should fly off into space. But they didn’t. 

Rubin was left with two possible explanations. Either Newton’s equations were wrong 
(something the scientific world would not accept) or the universe contained extra matter no 
astronomer had detected. 

She chose the second explanation and named this extra matter “dark matter” since it 
could not be seen or detected. Rubin calculated how much dark matter would be needed and 
how it would have to be distributed throughout the universe in order to make Newton’s 
equations correct. She found that 90 percent of the universe had to be dark matter. 

It took the rest of the scientific community a full decade to grudgingly accept Vera Ru- 
bin’ s results and the reality that most of the matter in the universe could not be seen or de- 
tected by any means available to humans. 

However, Vera Rubin’s work in that summer of 1970 changed every calculation and 
theory about the structure and origins of our universe. It vastly improved astronomers’ abil- 
ity to correctly calculate the distribution and motion of matter. Meanwhile — luckily — 
Newton’s laws of motion still survive. 

Fun Facts: NASA has tried to take a photograph of dark matter (some- 
TjV thing no once can see or directly detect) by combining X-ray telescope 
If images from the ROSAT satellite with other satellite imagery; the photo 
shown at http://heasarc.gsfc.nasa.gov/docs/rosat/gallery/display/darkmatter. 
html is the result. It could be the first photo of dark matter. 

More to Explore 

Golway , James. Where Is the Rest of the Universe ? (video). Los Angeles: KCET, 1991. 

Kraus, Lawrence. The Fifth Essence: The Search for Dark Matter. New York: Basic 
Books, 1993. 

. The Mystery of Missing Mass in the Universe. New York: Basic Books, 2000. 

Rubin, Vera. Bright Galaxies, Dark Matter. New York: American Institute of Physics, 
1997. 

St. Bartusiak, Marcia. Through a Universe Darkly. New York: HarperCollins, 1993. 

Tucker, Wallace. The Dark Matter. New York: Morrow Books, 1998. 

Yount, Lisa. Contemporary Women Scientists. New York: Facts on File, 1994. 


The Nature of Dinosaurs 


Year of Discovery: 1976 


What Is It? How dinosaurs really acted, moved, and lived. 
Who Discovered It? Robert Bakker 


Why Is This One of the 100 Greatest? 

Dinosaurs were plodding, cold-blooded monsters. They were sluggish, dull-gray, and 
so dumb they weren’t capable of decent parenting. That was the classical view of dinosaurs 
through the first half of the twentieth century. That was how dinosaurs were depicted in il- 
lustrations. That was what expert paleontologists believed. Robert Ba kk er shattered those 
beliefs. 

Robert Bakker was the first to claim that dinosaurs were warm blooded, colorful, and 
quick, intelligent, and agile. He also first proposed that birds were descended from dino- 
saurs. The images we see of dinosaurs — from Jurassic Park to science museum dis- 
plays — all owe their dinosaur concepts to Robert Bakker’s discoveries. Robert Bakker 
completely rewrote the book on dinosaurs. 


How Was It Discovered? 

A great revelation swept over Robert Bakker one night during his sophomore year at 
Yale University. As he walked through the darkened museum, faint bits of light caught the 
dinosaur skeletons and made them appear to move through the shadowed stillness. It oc- 
curred to Robert as he studied the familiar bones that these creatures had ruled the earth for 
165 million years. They couldn’t have been stupid, cold-blooded and sluggish. Intelligent 
mammals were around. They would have taken over unless the dinosaurs kept winning be- 
cause they were fundamentally better. 

Robert Bakker set out — all alone — to prove that the prevailing view of dinosaurs was 
completely wrong. Bakker turned to four sources of information to develop his case: compar- 
ative anatomy (comparing the size and shape of similar parts of different species), latitudinal 
zonation (where the animals live), the cumulative fossil record (all previously collected dino- 
saur bones and skeletons), and ecology (relationship of a species to its environment). 

For three years Bakker exhaustively studied the bones of mammals and found that 
they, as were dinosaur bones, were rich in blood vessels and lacked growth rings — just the 
opposite of cold-blooded reptiles. He found that Cretaceous dinosaurs thrived in northern 
Canada where cold-blooded reptiles could not have survived. Finally he studied African 
and North American ecosystems and found that warm-blooded predators eat six to eight 

213 



214 The Nature of Dinosaurs 


times as much per pound of body weight as do reptile predators. By studying the fossil re- 
cord, Bakker found that the ratio of predators to herbivores in dinosaur ecosystems matched 
what would be expected of a warm-blooded ecosystem. 

Dinosaurs had to have been warm-blooded. Their bones, relative numbers, and loca- 
tions proved it. 

He studied the legs of zoo animals, comparing leg structure to how they moved. Did a 
chicken’s leg bend differently than a zebra’s? How did those differences relate to the differ- 
ent activity of each animal? How did form dictate function for each animal, and how did 
function dictate form? What did the shape of a dinosaur’s joints and the size of its bones say 
about how it must have moved and functioned? He tried to account for this motion and the 
implied probable muscle masses to control and move each bone in his drawings. 

He compared leg bone size, shape, and density for hundreds of modern animals with 
those of dinosaurs. He found that dinosaur leg bones closely matched the bone structure of 
running mammals — not those who sprint for 10 seconds when alarmed, but those who regu- 
larly run for 20 minutes. 

Dinosaurs were runners. Their structure proved it. That also meant that they were ag- 
ile. No sluggish, clumsy oaf would be a natural runner. 

Ba kk er again turned to the fossil record and found that very few baby and juvenile di- 
nosaur skeletons had been discovered. This meant that few died, which in turn meant that 
parent dinosaurs had to have been very successful at protecting, sheltering, and feeding 
their young. Dinosaurs were good parents. 

The old myths were shattered. Bakker published his findings while still a graduate stu- 
dent at Harvard. But it took another 20 years of intense data collection and analysis for the tide 
of belief to turn in Bakker’ s direction. Even after Bakker’ s discoveries revolutionized sci- 
ence’s views of dinosaurs, he was still viewed with suspicion as an untrustworthy radical. 

/f~^\ Fun Facts: Giant Brontosaurus became the most popular of all dinosaurs 
v_ # / in the late nineteenth and early twentieth centuries. Its name means 
tp “thunder lizard.’’ By 1970 some scientists claimed that “Brontosaurus” 
should not be used since it referred to three different species: 
Apatosaurus, Brachiosaurus, and Camarasaurus. The argument contin- 
ues, though it’s been 80 million years since any of the three thundered 
across the earth. 

More to Explore 

Bakker, Robert. The Dinosaur Heresies. New York: Morrow Books, 1988. 

. “Unearthing the Jurassic.” In Science Year 1995. New York: World Book, 1995. 

Daintith, John. Biographical Encyclopedia of Scien tists, Volume 1. Philadelphia: In- 
stitute of Physics Publishing, 1994. 

Krishtalka, Leonard. Dinosaur Plots. New York: William Morrow, 1999. 

Officer, Charles. The Great Dinosaur Extinction Controversy. Reading, MA, Addison 
Wasley, 1996. 

Stille, Darlene. “Dinosaur Scientist.” In Science Year 1992. New York: World Book, 
1993. 


Planets Exist Around 

Other Stars 


Year of Discovery: 1995 


What Is It? Planets — even planets like Earth — exist around other stars. 
Who Discovered It? Michel Mayor and Didier Queloz 


Why Is This One of the 100 Greatest? 

One of the great questions for humanity has always been: Are we alone? Science has 
long asked: Are we the only solar system with planets — and the only one with planets that 
could support life? The discovery of planets around other stars makes it likely that other 
planets exist capable of supporting life. 

Of great importance to astronomers, the discovery of other solar systems lets them test 
their theories on the origin of planets and solar systems. The discovery of distant planets has 
fundamentally changed how we perceive our place in the universe. 


How Was It Discovered? 

In the sixth century B.C., Greek scientist Anaximander was the first to theorize that 
other planets must exist. In 1600 Italian priest and astronomer Giordano Bruno was burned 
at the stake by the Catholic Church for professing the same belief. American astronomers 
were actively searching through giant telescopes for planets orbiting other stars by late the 
1940s. 

Michel Mayor was born in 1942 and even as a child was fascinated by stars and astron- 
omy. With his collaborator, Antoine Duquennoy, he joined the many astronomers search- 
ing for small objects in the universe. But Mayor searched not for planets, but for brown 
dwarfs — cool, dim objects thought to form like stars, but which failed to grow massive 
enough to support hydrogen fusion and thus never lit up with starry furnace and fire. Too 
big for planets, too small to become stars, brown dwarfs were a galactic oddity. 

Astronomers, however, had a problem: telescopes can’t see planets and brown dwarfs 
because they don’t give off light. Instead, astronomers searched for slight side-to-side wob- 
bles in the motion of a star caused by the gravitational tug of a large planet (or brown 
dwarf). 

Some tried to detect such wobble by carefully measuring the position of a star over the 
course of months or years. Others (Mayor included) looked for this wobble by using Dopp- 

215 



216 Planets Exist Around Other Stars 


ler shift and measuring tiny shifts on a spectrograph in the color of the light coming from a 
star that would be the result of changes in the star’s motion toward or away from Earth. 

Following the death of Duquennoy in 1993, Mayor teamed with graduate student 
Didier Queloz and developed a new, more sensitive spectrograph to search for brown 
dwarfs. Their new spectrograph was capable of measuring velocity changes as small as 13 
meters per second — about the same as the wobble in our sun’s motion caused by Jupiter’s 
gravitational tug. 

But everyone assumed that such massive planets would take years to orbit a star (as 
they do in our system). Thus the wobble from a planet’s tug would take years of data to no- 
tice. It never occurred to Mayor to use his new spectrograph and a few months’ worth of 
time on a telescope to search for a planet. 

Beginning in April 1994, using the Haute-Provence Observatory in southern France, 
Mayor and Queloz tested their new spectrograph on 142 nearby stars, hoping to detect a 
wobble that would indicate a massive nearby object like a brown dwarf. In January 1995 
one star, 51 Peg (the fifty-first brightest star in the constellation Pegasus) caught Queloz’s 
eye. It wobbled. It wobbled back and forth every 4.2 days. 

They tested the star’s light to make sure it didn’t pulse. They tested to see if sun spots 
might create an apparent wobble. The tested to see if 5 1 Peg puffed up and contracted to cre- 
ate the appearance of wobble. Nothing could account for 51 Peg’s wobble except for a siz- 
able orbiting object. 

From the amount of 5 1 Peg’ s wobble they calculated the mass of the object and knew it 
was too small to be a brown dwarf. It had to be a planet! They had discovered a planet out- 
side our solar system. 

By 2005, several hundred other planets had been located — gas giants speeding around 
Mercury-sized orbits; some rocky planets in cozy, not-too-hot-and-not-too-cold orbits; 
even some drifting free through space without a star to circle. Earth is certainly not alone. 
Mayor and Queloz were the first to discover proof of this spectacular reality. 

(f~\ Fun Facts: If only one star in ten has planets (and current knowledge in- 
dicates that at least that many do), if the average star with planets has at 
W least three, and if only one in every hundred are rocky planets in life-sus- 
taining orbits (and recent discoveries indicate that to be the case), then 
there are at least 300,000 planets capable of supporting life in our galaxy 
alone! 


More to Explore 

Adler, Robert. Science Firsts. New York: John Wiley & Sons, 2002. 

Boss, Alan. Looking for Earths: The Race to Find New Solar Systems. New York: John 
Wiley & Sons, 1998. 

Croswell, Ken. Planet Quest: The Epic Discovery of Alien Solar Systems. New York: 
Free Press, 2002. 


More to Explore 217 


Goldsmith, Donald. Worlds Unnumbered: The Search for Extrasolar Planets. 
Sausalito, CA: University Science Books, 2000. 

Halpren, Paul. The Quest for Alien Planets: Exploring Worlds Outside the Solar Sys- 
tem. New York: Plenum, 1999. 

Lemonick, Michael. Other Worlds: The Search for Life in the Universe. New York: Si- 
mon & Schuster, 2001. 


Accelerating Universe 


Year of Discovery: 1998 


What Is It? Our universe is not only expanding; the rate at which it expands is 
speeding up, not slowing down as had been assumed. 

Who Discovered It? Saul Perlmutter 


Why Is This One of the 100 Greatest? 

A great debate began after Edwin Hubble discovered that the universe is expanding: Is 
that expansion slowing so that it will eventually stop and the universe will begin to col- 
lapse? Saul Perlmutter discovered that the expansion of the universe is actually accelerat- 
ing, shattering all existing scientific models of the motion of the universe. The universe is 
expanding faster now than it ever has before. It is tearing itself apart. Gravity is not slowing 
the expansion as it is supposed to. 

This discovery has created a monumental shift in how scientists view the universe, its 
past, and its future. It has affected the calculations of the Big Bang and even scientists’ view 
of what makes up the universe. The Journal of Science called this discovery the 1998 
“Breakthrough of the Year.” 


How Was It Discovered? 

Edwin Hubble discovered that the universe was expanding in 1926. Scientists built 
new models that assumed that the expansion was slowing down as gravity tugged on stars 
and galaxies, pulling them back toward each other. 

This model seemed logical. However, a few, highly technical problems existed with 
the mathematics associated with this model. Einstein tried to explain these problems by cre- 
ating something he called the “cosmological constant” — a force that opposed gravity. But 
he then rejected the idea as his greatest scientific blunder. 

After receiving a Ph.D. in physics in 1986, Saul Perlmutter worked at Lawrence 
Berkeley National Laboratory and headed the Supernova Cosmology Project (SCP). This 
group used the Hubble Space Telescope to find and study distant supernovae (exploding 
stars). They chose supernovae because they are the brightest objects in the universe. Type la 
supemovae produce a constant amount of light, and it is believed that all la supernovae 
shine at about the same brightness. This made them ideal for Perlmutter’ s study. 

Over the 10-year period from 1987 to 1997, Perlmutter developed a technique to iden- 
tify supernovae in distant galaxies and to analyze the light they produce. His team searched 
tens of thousands of galaxies to find a half dozen type la supernovae. 

218 



More to Explore 219 


When Perlmutter found an la supernova, he measured its brightness to determine its 
distance from Earth. (The brighter it is, the closer it is.) Perlmutter also measured the red 
shift of the supernova’ s light. This is a technique based on Doppler shifts. If a star is moving 
toward Earth, its light is compressed and its color shifts a little toward blue. If the star is 
moving away, its light is stretched and the color shifts toward red. The faster the star is mov- 
ing, the greater its color shift. By measuring the supernova’ s red shift, Perlmutter could cal- 
culate the star’s velocity away from Earth. 

Now came the hard part. Other factors could account for a red shift, and Perlmutter had 
to prove that the red shifts he measured were the result of only the star’s motion away from 
Earth. Space dust can absorb some light and shift its color. Some galaxies have an overall 
color hue that could distort the color of the light coming from a supernova. Each of a dozen 
possible sources of error had to be explored, tested, and eliminated. 

Finally, in early 1998, Perlmutter had collected reliable distance and velocity data for a 
dozen la supernovae spread across the heavens. All were moving at tremendous speeds 
away from Earth. 

Perlmutter used mathematical models to show that these galaxies couldn’t have been 
traveling at their current speeds ever since the Big Bang. If they had, they would be much 
farther away than they really are. The only way Perlmutter’ s data could be correct was for 
these galaxies to now be traveling outward faster than they had in the past. 

The galaxies were speeding up, not slowing down. The universe had to be expanding 
at an accelerating rate! 

Perlmutter’ s discovery showed that some new and unknown force (named “dark en- 
ergy” by Michael Turner in 2000) must be pushing matter (stars, galaxies, etc.) outward. 
More recent research using new specially designed satellites has shown that the universe is 
filled with this “dark energy.” (Some estimates say that two-thirds of all energy in the uni- 
verse is dark energy.) Over the next few years this new discovery will rewrite human theo- 
ries of the origin and structure of the universe. 


Adair, Rick. Scientific Information about the Universe and the Scientific Theories of 
the Evolution of the Universe: An Anthology of Current Thought. Cherry Hill, NJ: 
Rosen Central, 2005. 

Anton, Ted. Bold Science: Seven Scien tists Who Are Changing Our World. New York: 
W. H. Freeman, 2001. 

Couper, Heather. DK Space Encyclopedia. New York: DK Publishers, 2001. 

Gribbin, John. The Birth of Time: How Astronomers Measured the Age of the Uni- 
verse. New Haven, CT: Yale University Press, 2001. 

. EYEWITNESS: Time and Space. New York: DK Publishers, 2000. 

Kerrod, Robin. The Way the Universe Works. New York: DK Publishers, 2006. 



y Fun Facts: A new $20 million telescope is being built at the South Pole 
J to study and explain why the universe is accelerating, since this discov- 
• ery violates all existing theories about the birth and expansion of the uni- 
verse. The telescope will become operational in 2007. 


More to Explore 


Human Genome 


Year of Discovery: 2003 


What Is It? A detailed mapping of the entire human DNA genetic code. 
Who Discovered It? James Watson and J. Craig Venter 


Why Is This One of the 100 Greatest? 

Deciphering the human genetic code, the human genome, has been called the first 
great scientific discovery of the twenty-first century, the “Holy Grail” of biology. DNA is 
the blueprint for constructing, operating, and maintaining a living organism. It directs the 
transformation of a fertilized egg into a complete and complex human being. Deciphering 
that code is the key to understanding how cells are instructed to develop and grow, the key 
to understanding the development of life itself. 

Because the human genome is unimaginably complex, it seemed impossible to deci- 
pher the three billion elements of this molecular code. Yet this Herculean effort has already 
led to medical breakthroughs in genetic defects, disease cures, and inherited diseases. It is 
the key to future discoveries about human anatomy and health. Understanding this genome 
vastly increased our appreciation of what makes us unique and what connects us with other 
living species. 


How Was It Discovered? 

Austrian monk Gregor Mendel discovered the concept of heredity in 1865, launching 
the field of genetics. In 1953 Francis Crick and James Watson discovered the double helix 
shape of the DNA molecule that carried all genetic instructions. 

The problem was that there were billions of genetic instructions carried on the com- 
plete human genetic code, or genome. Understanding it all seemed a physically impossible 
task. Sequencing the entire human genome was a project 20,000 times bigger and harder 
than any biological project attempted to that time. 

Charles De Lisi at the U.S. Department of Energy (DOE) was the first to gain govern- 
ment funds to begin this monumental process, in 1987. By 1990, the DOE had joined with 
the National Institutes of Health (NIH) to create a new organization, the International Hu- 
man Genome Sequencing Consortium (IHGSC). James Watson (of DNA discovery fame) 
was asked to head the project and was given 15 years to accomplish this monumental task. 


220 



How Was It Discovered? 221 


At that time, scientists believed that human DNA contained about 100,000 genes 
spread along 23 chromosomes locked onto DNA’s double helix, held together by over 3 bil- 
lion base pairs of molecules. Watson’s task was to identify, interpret, and sequence every 
gene on every chromosome, as well as every one of those billions of base pairs. 

Certainly, the ability to identify and sequence individual pairs existed. Watson’s prob- 
lem was one of size. Using the existing (1990) technology, it would take thousands of years 
for all existing labs to complete the identification and sequencing of three billion pairs. 

Watson decided to start with large-scale maps of what was known about chromosomes 
and work down toward the details of individual pairs. He directed all IHGSC scientists to 
work toward creating physical and linking maps of the 23 chromosomes. These maps would 
provide an overview of the human genome and would include only those few “snippets” of 
actual gene sequences that were already known. 

By 1994 this first effort was complete. Watson ordered IHGSC scientists to map the 
complete genome of the simplest and best-known life forms on Earth to refine their tech- 
nique before attempting to work on the human genome. IHGSC scientists chose fruit flies 
(studied extensively since 1910), e. coli (the common intestinal bacterium), bread molds, 
and simple nematodes (tiny oceanic worms). In the mid-1990s, work began on mapping the 
tens of millions of base pairs in these simple genomes. 

However, not all biologists agreed with this approach. J. Craig Venter (a gene se- 
quencer at the Institutes of Health) believed that scientists would waste precious years fo- 
cusing on Watson’s “big picture” and should instead sequence as many specific parts of the 
genome as they could and piece these individual sequences together later. 

A war began between Watson (representing the “top down” approach) and Venter 
(representing the “bottom up” approach). Accusations and ugly words erupted from both 
sides at congressional hearings, at funding meetings, and in the press. 

Venter quit his government position and formed his own company to develop as much 
of the genome sequence as he could ahead of IHGSC’ s effort. In 1998 Venter shocked the 
world by announcing that he would use linked supercomputers to complete his sequencing 
of the entire human genome by 2002, three years ahead of IHGSC’s timetable. 

In early 2000 President Clinton stepped in to end the war and merged both sides into a 
unified genome effort. In 2003 this merged team released their preliminary report, detailing 
the entire sequence of the human genome. In written form, that genome would fill 150,000 
printed pages (500 books, each 300 pages long). 

Surprisingly, these scientists found that humans have only 25,000 to 28,000 genes 
(down from the previously believed 100,000). A human’s genetic sequence is only a few 
percent different from that of many other species. 

Even though the information on this genetic sequence is only a few years old, it has al- 
ready helped medical researchers make major advances on dozens of diseases and birth de- 
fects. Its full value will be seen in medical breakthroughs over the next 20 to 50 years. 


Fun Facts: If the DNA sequence of the human genome were compiled in 
books, the equivalent of 200 volumes the size of a Manhattan telephone 
book (at 1 ,000 pages each) would be needed to hold it all. 


222 Human Genome 


More to Explore 

Boon, Kevin. Human Genome Project: What Does Decoding DNA Mean for Us? 
Berkeley Heights, NJ: Enslow, 2003. 

Brooks, Martin. Get a Grip on Genetics. New York: Time-Life Books, 1999. 

Marshall, Elizabeth. The Human Genome Project: Cracking the Code Within Us. New 
York: Scholastic Library, 2001. 

Sloan, Christopher. The Human Story: Our Evolution from Prehistoric Ancestors to 
Today. Washington, DC. National Geographic Society, 2004. 

Toriello, James. Human Genome Project. Cherry Hill, NJ: Rosen Publishing, 2003. 


References 


These book and Internet sources are good general references on scientific discovery, 
on the process of scientific investigation, on the history of scientific discoveries, and on im- 
portant scientists. 


Book Sources 

Aaseng, Nathan. Twentieth-Century Inventors. New York: Facts on File, 1996. 

Adler, Robert. Science Firsts, New York: John Wiley & Sons, 2002. 

. Medical Firsts. New York: John Wiley & Sons, 2004. 

Anton, Ted. Bold Science: Seven Scientists Who Are Changing Our World. New York: 
W. H. Freeman, 2001. 

Ashby, Ruth. Herstory. New York: Penguin Books, 1995. 

Asimov, Isaac. Asimov’s Chronology of Science and Discovery. New York: Harper & 
Row, 1994. 

Atkins, Peter, Galileo’s Finger: The Ten Great Ideas of Science. New York: Random 
House, 2004. 

Aubrey, John. Brief Lives, Volumes I and II. New York: Clarendon Press, 1998. 

Badger, Mark. Two-Fisted Science. New York: G. T. Labs, 2001. 

Berlinski, David. Newton ’s Gift. New York: Free Press, 2000. 

Beshore, George. Science in Ancient China. New York: Franklin Watts, 1996. 

Boorstin, Daniel. The Discoverers: A History of Man ’s Search to Know His World and 
Himself New York: Random House, 1997. 

Brockman, John. Curious Minds: How a Child Becomes a Scientist. New York: 
Knopf, 2005. 

Brodie, James. Created Equal: The Lives and Ideas of Black American Inventors. New 
York: William Morrow, 1999. 

Bryan, Jenny. The History of Health and Medicine. Florence, KY: Thompson Learn- 
ing, 1999. 

Bunch, Bryan. The History of Science and Technology. New York: Houghton Mifflin, 
2004. 

Chang, Laura, ed. Scientists at Work. New York: McGraw-Hill, 2000. 


223 


224 References 


Clark, Donald. Encyclopedia of Great Inventors and Discoveries. London: Marshall 
Cavendish Books, 1991. 

Cohen, Bernard. Revolutions in Science. Cambridge, MA: Harvard University Press, 
1995. 

Collins, H., and T. Pinch. What You Should Know About Science. New York: Cam- 
bridge University, 1998. 

Conrad, Lawrence, et al. The Western Medical Tradition: 800 BC to 1900 AD. New 
York: Cambridge University Press, 1999. 

Cropper, William. Great Physicists. New York: Oxford University Press, 2001. 

Day, Lance, ed. Biographical Dictionary of the History of Technology. New York: 
Routledge, 1996. 

Diagram Group. Facts on File Chemistry Handbook. New York: Facts on File, 2000. 

. Facts on File Physics Handbook. New York: Facts on File, 2006. 

Downs, Robert. Landmarks in Science. Englewood, CO: Libraries Unlimited, 1993. 

Dreyer, J. A History of Astronomy from Thales to Kepler. New York: Dover, 1993. 

Ferguson, Keith. Measuring the Universe: The Historical Quest to Quantify Space. 
New York: Headline Books, 1999. 

Fox, Ruth. Milestones in Medicine. New York: Random House, 1995. 

Francis, Raymond. The Illustrated Almanac of Science, Technology, and Invention. 
New York: Plenum Trade, 1997. 

Frontier Press Co. Great Masters of Achievement in Science and Discovery. Whitefish, 
MT: Kessinger, 2005. 

Gallant, Roy. The Ever-Changing Atom. New York: Benchmark Books, 2000. 

Garwin, Laura. A Century of Nature: Twenty-One Discoveries That Changed Science 
and the World. Chicago: University of Chicago Press, 2003. 

Gibbs, C.R. Black Inventors from Africa to America. Silver Springs, MD: Three Di- 
mensional, 1999. 

Gratzer, Walter. Eurekas and Euphorias. New York: Oxford University Press, 2004. 

Greenstein, George. Portraits of Discovery: Profiles in Scientific Genius. New York: 
John Wiley & Sons, 1997. 

Gribbin, John. The Scientists: A History of Science Told through the Lives of Its Great- 
est Inventors. New York: Random House, 2002. 

Hall, Ruppert. A Brief History of Science. Iowa City: Iowa State Press, 1999. 

Hammond, Allen, ed. A Passion to Know: 20 Profiles in Science. New York: 
Scribner’s, 1995. 

Hatt, Christine. Scientists and Their Discoveries. New York: Franklin Watts, 2001. 


Haven, Kendall. Amazing American Women. Englewood, CO: Libraries Unlimited, 
1996. 


References 225 


. Marvels of Science. Englewood, CO: Libraries Unlimited, 1994. 

. The 100 Greatest Science Inventions of All Time. Westport, CT : Libraries Un- 
limited, 2005. 

. That’s Weird! Awesome Science Mysteries. Boulder, CO: Lulcrum Re- 
sources, 2000. 

. Women at the Edge of Discovery. Englewood, CO: Libraries Unlimited: 

2003. 

Haven, Kendall, and Donna Clark. The 100 Most Popular Scientists for Young Adults. 
Westport, CT: Libraries Unlimited, 2001. 

Hawking, Steven. A Brief History of Time. New York: Bantam, 1996. 

Hawley, John, and Katherine Holcomb. Foundations of Modern Cosmology. New 
York: Oxford University Press, 1998. 

Hayden, Robert. 9 African American Inventors. New York: Twenty-Lirst Century 
Books, 1992. 

Heilbron, John. The Oxford Companion to the History of Modern Science. New York: 
Oxford University Press, 2003. 

Hooft, G. In Search of the Ultimate Building Blocks. New York: Cambridge Univer- 
sity Press, 1997. 

Huff, Toby. The Rise of Early Modern Science. New York: Cambridge University 
Press, 1993. 

Irwin, Keith. The Romance of Chemistry. New York: Viking Press, 1996. 

Jones, Alexander, ed. Cambridge History of Science: Ancient Science. New York: 
Cambridge University Press, 2006. 

Jungk, R. Brighter Than a Thousand Suns: A Personal History of the Atomic Scien- 
tists. New York: Harcourt Brace, 1998. 

Kass-Simon, Amy. Women of Science: Righting the Record. Bloomington: Indiana 
University Press, 1996. 

Koestler, Arthur. The Sleepwalkers: A History of Man’s Changing Vision of the Uni- 
verse. London: Hutchinson & Co., 1999. 

Levere, Trevor. Transforming Matter : A History of Chemistry from Alchemy to the 
Buckyball. Baltimore, MD: Johns Hopkins University Press, 200 

Lomask, Milton. Invention and Technology Great Lives. New York: Charles 
Scribner’s Sons, 1994. 

Maddox, John. What Remains to Be Discovered. New York: Tree Press, 1998. 

Mather, John, and John Boslough. The Very First Light: The True Inside Story of the 
Scientific Journey Back to the Dawn of the Universe. New York: Basic Books, 

1996. 

McGrayne, Sharon. Nobel Prize Women of Science. New York: Birch Lane Press, 

1997. 


226 References 


McNeil, Ian. An Encyclopedia of the History of Technology. New York: Routledge, 
1996. 

Messadie, Gerald. Great Scientific Discoveries. New York: Chambers, 2001. 

Nader, Helen. Rethinking the World: Discovery and Science in the Renaissance. 
Bloomington: Indiana University Press, 2002. 

National Geographic Society. Inventors and Discoveries: Changing Our World. 
Washington, DC: National Geographic Society, 1998. 

Nelson, Clifford. Discoveries in Science. New York: Harcourt Brace, 1994. 

North, John. The Norton History of Astronomy and Cosmology. New York: Norton, 

1995. 

Pais, Abraham. The Genius of Science: A Portrait Gallery. New York: Oxford Univer- 
sity Press, 2000. 

Palmer, Eric. Philosophy of Science and History of Science. New York: Xlibris Corp., 
2000 . 

Parker, Steve. Galileo and the Universe. New York: HarperCollins Children’s Books, 

1996. 

Perkowitz, Sidney. Empire of Light: A History of Discovery in Science. New York: 
National Academies Press, 1998. 

Philbin, Tom. The 100 Greatest Inventions of All Time. New York: Citadel Press, 
2003. 

Porter, Theodore. The Cambridge History of Science. New York: Cambridge Univer- 
sity Press, 2003. 

Pullman, Bernard. The Atom in the History of Human Thought. New York: Oxford 
University Press, 1999. 

Pyenson, Lewis, and Susan Pyenson. Servants of Nature, New York: HarperCollins, 

1999. 

Rattanski, P. M. Pioneers of Science and Discovery. Charleston, WV: Main Line 
Books, 1997. 

Schlessinger, Bernard, and June Schlessinger. The Who ’s Who of Nobel Prize Winners 
1901-1999. New York: Oryx Press, 2001. 

Shepherd, Linda. Lifting the Veil: The Feminine Face of Science. Boston: Shambala, 

2000 . 

Sherrow, Victoria. Great Scientists. New York: Lacts on Lile, 1998. 

Silvers, Robert. Hidden Histories of Science. New York: New York Review of Books, 
2003. 

Singh, Simon. The Science Book: 250 Milestones in the History of Science. London: 
Cassell, 2001. 

Smith, Roger. The Norton History of Human Sciences. New York. W. W. Norton, 

1997. 


References 227 


Snedden, Robert. Scientists ancl Discoveries. Portsmouth, NH: Heinemann, 2001. 

Stille, Darlene. Extraordinary Women Scientists. Chicago: Children’s Press, 1999. 

Sturtevant, A. H. A History of Genetics. Cold Spring Harbor, NY: Cold Spring Harbor 
Laboratory Press, 2001. 

Suplee, Curt. Milestones of Science. Washington, DC: National Geographic Society, 
2000 . 

Temple, Robert. The Genius of China: 3,000 Years of Science, Discovery, and Inven- 
tion. New York: Simon & Schuster, 2000. 

Veglahn, Nancy. Women Scientists. New York: Facts on File, 1997. 

Whitfield, Peter. Landmarks in Western Science. London: British Library, 1999. 

Yenne, Bill. 100 Inventions That Shaped World History. New York: Bluewood Books, 
1993. 

Yuval, Neeman, and Yoram Kirsh. The Particle Hunters. Cambridge, MA: Harvard 
University Press, 1999. 


Internet Web Site Sources 

These sites focus on the history of science and discoveries in general. Conduct your 
own searches for specific scientific topics, fields, or periods. 

www.echo.gmu.edu/center 

www.hssonline.org/ 

www.depts.washington.edu/hssexec/ 

www.bshs.org.uk 

www2.lib.udel.edu/subj/hsci/internet.htm 

www.fordham.edu/halsall/science/sciencesbook.html 

www2.sjsu.edu/elementaryed/ejlts/archives/diversity/hampton.htm 

www.aip.org/history/web-link.htm 

www.fas.harvard.edu/~hsdept/ 

www.mpiwg-berlin.mpg.de 

www.hps.cam.ac.uk/whipple/ 

www.mdx.ac.uk/www/study/sshtim.htm 

hos.princeton.edu 

www.astro.uni-bonn.de/~pbrosche/hist_sci/hs_general.html 

www.mhs.ox.ac.uk/exhibits/ 

www. smithsonianeducation.org/ 

www.hstm.imperial.ac.uk/rausingschol.htm 

www.clas.ufl.edu/users/rhatch/pages/10-HisSci/links/index.htm 

hpst.stanford.edu/ 

www.library.ualberta.ca/subject/historyscience/guide/index.cfm 
w w w . sil. si .edu/Libraries/Dibner/index. htm 
www.physlink.com/Education/History.cfm 

www.si.edu/history_and_culture/history_of_science_and_technology/ 

www.mla-hhss.org/histlink.htm 



Appendix 1: Discoveries 
by Scientific Field 


These tables list the 100 greatest science discoveries divided into their appropriate 
fields of science so that readers can easily identify the individual discoveries that relate to 
the same area. Within each field inventions are listed chronologically. 


Physical Sciences 


Discovery 

Discovering Scientist 

Year 

Page 

Astronomy 

Sun-centered universe 

Copernicus, Nicholaus 

1520 

5 

Planets’ true orbits 

Kepler, Johannes 

1609 

11 

Other planets have moons 

Galilei, Galileo 

1610 

13 

Distance to the sun 

Cassini, Giovanni 

1672 

27 

Galaxies 

Herschel, William 

1750 

36 


Wright, Thomas 

1750 

36 

Black hole 

Schwarzschild, Karl 

1916 

140 


Wheeler, John 

1971 

141 

Expanding universe 

Hubble, Edwin 

1926 

150 

The Big Bang 

Gamow, George 

1948 

185 

Quasar 

Sandage, Allan 

1963 

205 

Pulsar 

Bell, Jocelyn 

1967 

205 


Hewish, Antony 

1967 

205 

Dark matter 

Rubin, Vera 

1970 

211 

Planets around other stars 

Mayor, Michel 

1995 

215 


Queloz, Didier 

1995 

215 

Universe is accelerating 

Perlmutter, Saul 

1998 

218 

Chemistry 

Boyle’s Law 

Boyle, Robert 

1662 

19 

Oxygen 

Priestley, Joseph 

1774 

43 

Electrochemical bonding 

Davy, Humphrey 

1806 

61 

Molecules 

Avogadro, Amedeo 

1811 

63 

Atomic light signatures 

Bunsen, Robert 

1859 

81 


Kirchhoff, Robert 

1859 

81 


229 


230 Appendix 1: Discoveries by Scientific Field 


Discovery 

Discovering Scientist 

Year 

Page 

Periodic Table 

Mendeleyev, Dmitri 

1880 

90 

Radioactivity 

Curie, Marie and Pierre 

1901 

105 

Radioactive dating 

Boltwood, Bertram 

1907 

119 

Isotopes 

Soddy, Frederick 

1913 

133 

Physics 

Levers and buoyancy 

Archimedes 

260 B.C. 

3 

Law of falling objects 

Galilei, Galileo 

1598 

9 

Air pressure 

Torricelli, Evangelista 

1640 

17 

Universal gravitation 

Newton, Isaac 

1666 

23 

Laws of motion 

Newton, Isaac 

1687 

31 

Nature of electricity 

Franklin, Benjamin 

1752 

38 

Conservation of matter 

Lavoisier, Antoine 

1789 

47 

Nature of heat 

Rumford, Count 

1790 

49 

Infrared 

Herschel, Frederick 

1800 

55 

Ultraviolet 

Ritter, Johann 

1801 

55 

Atoms 

Dalton, John 

1802 

59 

Electromagnetism 

Oersted, Hans 

1820 

65 

Calorie 

Joule, James 

1843 

71 

Conservation of energy 

Helmholtz, H. von 

1847 

73 

Doppler effect 

Doppler, Christian 

1848 

75 

Electromagnetic radiation 

Maxwell, James 

1864 

83 

X-rays 

Roentgen, Wilhelm 

1895 

95 

Energy equation 

Einstein, Albert 

1905 

111 

Relativity 

Einstein, Albert 

1905 

114 

Superconductivity 

Onnes, Heike 

1911 

128 

Atomic bonding 

Bohr, Niels 

1913 

131 

Quantum theory 

Born, Max 

1925 

148 

Uncertainty Principle 

Heisenberg, Werner 

1927 

153 

Speed of light 

Michelson, Albert 

1928 

155 

Antimatter 

Dirac, Paul 

1929 

160 

Neutron 

Chadwick, James 

1932 

163 

Strong force 

Yukawa, Hideki 

1937 

171 

Nuclear fission 

Meitner, Lise 

1939 

178 


Hahn, Otto 

1939 

178 

Semiconductor transistor 

Bardeen, John 

1947 

183 

Definition of information 

Shannon, Claude 

1948 

188 

Nuclear fusion 

Bethe, Hans 

1951 

192 


Spitzer, Lyman 

1951 

192 

Quarks 

Gell-Mann, Murry 

1962 

203 

Weak force 

Rubbia, Carlo 

1983 

171 


Appendix 1: Discoveries by Scientific Field 231 


Earth Sciences 


Discovery 

Discovering Scientist 

Year 

Page 

Gulf Stream 

Franklin, Benjamin 

1770 

40 


Humbolt, A. von 

1814 

41 

Erosion (weathering) 

Hutton, James 

1792 

51 

Ice ages 

Agassiz, Louis 

1837 

69 


Milankovich, Milutin 

1920 

70 

Atmospheric layers 

de Bort, L. Teisserenc 

1902 

107 

Fault lines 

Reid, Harry 

1911 

126 

Earth’s core 

Gutenberg, Beno 

1914 

136 

Continental drift 

Wegener, Alfred 

1915 

138 

Ecosystem 

Tansley, Arthur 

1935 

169 

Seafloor spreading 

Hess, Harry 

1957 

199 

Chaos theory 

Lorenz, Ed 

1960 

201 


Life Sciences 


Discovery 

Biology 

Discovering Scientist 

Year 

Page 

Cells 

Hooke, Robert 

1665 

21 

Fossils 

Steno, Nicholas 

1669 

25 

Bacteria 

Leeuwenhoek, Anton van 

1680 

29 

Taxonomy system 

Linnaeus, Carl 

1735 

33 

Photosynthesis 

Ingenhousz, Jan 

1779 

45 

Dinosaur fossils 

Buckland, William 

1824 

67 


Mantell, Gideon 

1824 

67 

Germ theory 

Pasteur, Louis 

1856 

77 

Deep-sea life 

Thomson, Charles 

1870 

88 

Cell division 

Flemming, Walther 

1882 

92 

Virus 

Beijerinick, Martinus 

1898 

101 


Ivanovsky, Dmitri 

1898 

101 

Cell structure 

Claude, Albert 

1933 

165 

Origins of life 

Miller, Stanley 

1952 

194 

Nature of dinosaurs 

Bakker, Robert 

1976 

213 


232 Appendix 1: Discoveries by Scientific Field 


Discovery 

Discovering Scientist 

Year 

Page 

Evolution and Human Anatomy 



Human anatomy 

Vesalius, Andreas 

1543 

7 

Evolution 

Darwin, Charles 

1858 

79 

Heredity 

Mendel, Gregor 

1865 

86 

Mitochondria 

Benda, Carl 

1898 

103 

Genetic mutations 

Morgan, Thomas 

1909 

121 

N eurotransmitters 

Loewi, Otto 

1921 

144 


Walder-Hartz, Heinrich 

1921 

144 

Human evolution 

Dart, Raymond 

1924 

146 

Coelacanth 

Smith, J. L. B 

1938 

176 

Jumping genes 

McClintock, Barbara 

1950 

190 

DNA 

Crick, Francis 

1953 

196 


Watson, James 

1953 

196 


Franklin, Rosalind 

1953 

197 

Complete evolution 

Margulis, Lynn 

1967 

208 

Human genome 

Venter, Craig 

2003 

220 


Watson, James 

2003 

220 

Medical Science 




Human circulatory system 

Harvey, William 

1628 

15 

Vaccinations 

Montagu, Lady Mary Wortley 

1798 

53 


Jenner, Edward 

1794 

53 

Anesthesia 

Davy, Humphry 

1801 

57 

Chloroform (anesthesia) 

Simpson, Young 

1801 

57 

Ether (anesthesia) 

Long, Crawford 

1801 

58 

Blood types 

Landsteiner, Karl 

1897 

97 

Hormones 

Bayliss, William 

1902 

109 


Starling, Ernest 

1902 

109 

Vitamins 

Hopkins, Frederick 

1906 

117 


Eijkman, Christiaan 

1906 

117 

Antibiotics 

Ehrlich, Paul 

1910 

124 

Insulin 

Banting, Frederick 

1921 

142 

Penicillin 

Flemming, Alexander 

1928 

158 

Genes 

Beadle, George 

1934 

167 

Metabolism (Krebs Cycle) 

Krebs, Hans 

1938 

174 

Blood plasma 

Drew, Charles 

1940 

181 


Appendix 2: Scientists 


This table is an alphabetical list of the scientists featured in the discussions of the 100 
greatest discoveries. Each is listed with his or her discovery and the year the discovery was 
made. 


Name 

Discovery 

Year 

Page 

Abel, John 

Hormones 

1898 

109 

Agassiz, Louis 

Ice ages 

1837 

69 

Archimedes 

Levers and buoyancy 

260 B.C. 

3 

Avogadro, Amedeo 

Molecules 

1811 

63 

Bakker, Robert 

Nature of dinosaurs 

1976 

213 

Banting, Frederick 

Insulin 

1921 

142 

Bardeen, John 

Semiconductor transistor 

1947 

183 

Bayliss, William 

Hormones 

1902 

109 

Beadle, George 

Genes 

1934 

167 

Beijerinick, Martinus 

Virus 

1898 

101 

Bell, Jocelyn 

Pulsar 

1967 

205 

Benda, Carl 

Mitochondria 

1898 

103 

Bethe, Hans 

Nuclear fusion 

1939 

192 

Bohr, Niels 

Atomic bonding 

1913 

131 

Boltwood, Bertram 

Radioactive dating 

1907 

119 

Bom, Max 

Quantum theory 

1925 

148 

Boyle, Robert 

Boyle’s law 

1662 

19 

Buckland, William 

Dinosaur fossils 

1824 

67 

Bunsen, Robert 

Atomic light signatures 

1859 

81 

Cassini, Giovanni 

Distance to the sun 

1672 

27 

Chadwick, James 

Neutron 

1932 

163 

Claude, Albert 

Cell structure 

1933 

165 

Copernicus, Nicholaus 

Sun-centered universe 

1520 

5 

Courtenay-Latimer, M. 

Coelacanth 

1938 

176 

Crick, Francis 

DNA 

1953 

196 

Curie, Marie and Pierre 

Radioactivity 

1901 

105 

Dalton, John 

Atoms 

1802 

59 

Dart, Raymond 

Human evolution 

1924 

146 

Darwin, Charles 

Evolution 

1858 

79 

Davy, Humphry 

Anesthesia 

1801 

57 

Davy, Humphry 

Electrochemical bonding 

1806 

61 

de Bort, Leon Teisserenc 

Atmospheric layers 

1902 

107 


233 


234 Appendix 2: Scientists 


Name 

Discovery 

Year 

Page 

Dirac, Paul 

Antimatter 

1929 

160 

Doppler, Christian 

Doppler effect 

1848 

75 

Drew, Charles 

Blood plasma 

1940 

181 

Ehrlich, Paul 

Antibiotics 

1910 

124 

Eijkman, Christiaan 

Vitamins 

1906 

117 

Einstein, Albert 

Energy equation 

1905 

111 

Einstein, Albert 

Relativity 

1905 

114 

Galilei, Galileo 

Faw of falling objects 

1598 

9 

Galilei, Galileo 

Other planets have moons 

1609 

11 

Gamow, George 

The Big Bang 

1948 

185 

Gell-Mann, Murry 

Quarks 

1962 

203 

Gutenberg, Beno 

Earth’s core 

1914 

136 

Fermi, Enrico 

Nuclear fission 

1939 

178 

Flemming, Alexander 

Penicillin 

1928 

158 

Flemming, Walther 

Cell division 

1882 

92 

Franklin, Benjamin 

Nature of electricity 

1752 

38 

Franklin, Benjamin 

Gulf Stream 

1770 

40 

Franklin, Rosalind 

DNA 

1953 

197 

Hahn, Otto 

Nuclear fission 

1939 

178 

Harvey, William 

Human circulatory system 

1628 

15 

Heisenberg, Werner 

Uncertainty Principle 

1927 

153 

Helmholtz, Hermann von 

Conservation of energy 

1847 

73 

Herschel, Frederick 

Infrared 

1800 

55 

Herschel, William 

Galaxies 

1750 

36 

Hess, Harry 

Seafloor spreading 

1957 

199 

Hewish, Antony 

Pulsar 

1967 

205 

Hodgkin, Dorothy 

Penicillin 

1942 

159 

Hooke, Robert 

Cells 

1665 

21 

Hopkins, Frederick 

Vitamins 

1906 

117 

Hubble, Edwin 

Expanding universe 

1926 

150 

Humbolt, Alexander von 

Gulf Stream 

1814 

41 

Hutton, James 

Erosion (weathering) 

1792 

51 

Ingenhousz, Jan 

Photosynthesis 

1779 

45 

Ivanovsky, Dmitri 

Virus 

1898 

101 

Jenner, Edward 

Vaccinations 

1794 

53 

Joule, James 

Calorie 

1843 

71 

Kepler, Johannes 

Planets’ true orbits 

1609 

11 

Kirchhoff, Robert 

Atomic light signatures 

1859 

81 

Krebs, Hans 

Metabolism (Krebs Cycle) 

1938 

174 

Fandsteiner, Karl 

Blood types 

1897 

97 

Favoisier, Antoine 

Conservation of matter 

1789 

47 


Appendix 2: Scientists 235 


Name 

Discovery 

Year 

Page 

Lehman, Inge 

Earth’s core 

1938 

137 

Leeuwenhoek, Anton van 

Bacteria 

1680 

29 

Linnaeus, Carl 

Taxonomy system 

1735 

33 

Long, Crawford 

Ether (anesthesia) 

1801 

58 

Loewi, Otto 

Neurotransmitters 

1921 

144 

Lorenz, Ed 

Chaos theory 

1960 

201 

Mantell, Gideon 

Dinosaur fossils 

1824 

67 

Margulis, Lynn 

Complete evolution 

1967 

208 

Mayor, Michel 

Planets around other stars 

1995 

215 

Maxwell, James 

Electromagnetic radiation 

1864 

83 

McClintock, Barbara 

Jumping genes 

1950 

90 

Meitner, Lise 

Nuclear fission 

1939 

178 

Mendel, Gregor 

Heredity 

1865 

86 

Mendeleyev, Dmitri 

Periodic Table 

1880 

90 

Michelson, Albert 

Speed of light 

1928 

155 

Milankovich, Milutin 

Ice ages 

1920 

70 

Miller, Stanley 

Origins of life 

1952 

194 

Montagu, Lady Mary 

Vaccinations 

1798 

53 

Morgan, Thomas 

Genetic mutations 

1909 

121 

Newton, Isaac 

Universal gravitation 

1666 

23 

Newton, Isaac 

Laws of motion 

1687 

31 

Oersted, Hans 

Electromagnetism 

1820 

65 

Onnes, Heike 

Superconductivity 

1911 

128 

Pasteur, Louis 

Germ theory 

1856 

77 

Perlmutter, Saul 

Universe is accelerating 

1998 

218 

Priestley, Joseph 

Oxygen 

1774 

43 

Queloz, Didier 

Planets around other stars 

1995 

215 

Reid, Harry 

Fault lines 

1911 

126 

Ritter, Johann 

Ultraviolet' 

1801 

55 

Roentgen, Wilhelm 

X-rays 

1895 

95 

Rubbia, Carlo 

Weak force 

1983 

171 

Rubin, Vera 

Dark matter 

1970 

211 

Rumford, Count 

Nature of heat 

1790 

49 

Sandage, Allan 

Quasar 

1963 

205 

Schwarzschild, Karl 

Black hole 

1916 

140 

Shannon, Claude 

Definition of information 

1948 

188 

Sharpey-Schafer, Edward 

Hormones 

1894 

109 

Simpson, Young 

Chloroform (anesthesia) 

1801 

57 

Smith, J. L. B. 

Coelacanth 

1938 

176 

Soddy, Frederick 

Isotopes 

1913 

133 

Spitzer, Lyman 

Nuclear fusion 

1951 

193 


236 Appendix 2: Scientists 


Name 

Starling, Ernest 
Steno, Nicholas 
Takamine, Jokichi 
Tansley, Arthur 
Tatum, Edward 
Thomson, Charles 
Torricelli, Evangelista 
Venter, Craig 
Vesalius, Andreas 
Walder-Hartz, Heinrich 
Watson, James 
Watson, James 
Wegener, Alfred 
Wheeler, John 
Wright, Thomas 
Yukawa, Hideki 


Discovery 

Hormones 

Fossils 

Hormones 

Ecosystem 

Genes 

Deep-sea life 
Air pressure 
Human genome 
Human anatomy 
Neurotransmitters 
DNA 

Human genome 
Continental drift 
Black holes 
Galaxies 
Strong force 


Year 

Page 

1902 

109 

1669 

25 

1900 

109 

1935 

169 

1934 

167 

1870 

88 

1640 

17 

2003 

220 

1543 

7 

1888 

144 

1953 

196 

2003 

220 

1915 

138 

1971 

141 

1750 

36 

1937 

171 


Appendix 3: The Next 40 


This table is a list of 40 important discoveries that almost made the final list of the 
greatest 100. Each is worthy of consideration, honor, and study. Pick one or more of these to 
research and describe. 


Earth is a sphere 

Aristotle 

387 B.C. 

The heavens are not fixed and 
unchanging 

Brahe 

1574 

The nature of light 

Galileo, Newton, Young, Einstein 

various years 

Compressibility of gasses 

Boyle 

1688 

Lift/fluid pressure 

Bernoulli 

1738 

Comets have predictable orbits 

Halley 

1758 

Hydrogen 

Cavendish 

1776 

Origin of the solar system 

Laplace 

1796 

Mass of the earth 

Cavendish 

1798 

Liquification of gasses 

Faraday 

1818 

Fingerprints, uniqueness of 

Purkinje 

1823 

Magnetic induction 

Faraday 

1831 

Age of the sun 

Helmholtz 

1853 

Sun is a gas 

Carrington 

1859 

Age of the earth 

Lyell (first), Holmes (accurate) 

1860, 1940 

Antiseptics 

Lister 

1863 

Plastics 

Hyatt 

1869 

Alternating current 

Tesla 

1883 

Bacteriology 

Koch 

1890 

Earth’s magnetic field reversals 

Brunhes 

1906 

Chemotherapy 

Ehrlich 

1906 

Cosmic radiation 

Hess 

1911 

Electroencephalogram 

Berger 

1924 

adjustrightBrucellosis bacterium 

Evans 

1925 

Exclusion principle 

Pauli 

1926 

Neutrino 

Pauli 

1926 

Galaxies emit radio waves 

Jansky 

1932 

Artificial radioactivity 

Curie and Joliot 

1934 

Cortisone 

Kendall 

1935 

Sulfa drugs 

Domagk 

1936 

Radiation therapy 

Priore 

1950 

Laser 

Townes and Gould 

1954/1957 


237 


238 Appendix 3: The Next 40 


Global warming 

Many 

late twentieth 

First cloning 

Gurden 

century 

1967 

Laetoli footprints (3.5 million 

Mary Leakey 

1973 

years old) 

’’Lucy” (3.2 million-year-old 

Donald Johnson 

1974 

skull) 

Non-oxygen-based deep sea life 

Ballard 

1977 

Dinosaur extinction (K-T 

Alvarez 

1979 

asteroid) 

Fluman retrovirus ITIV 

Gallo and Montagnier 

1982 

Toumai skull (6 to 7 million years 

Michel Brunet 

2002 

old) 


Index 


Absolute zero temperature 
superconductivity, 128-29 
Accelerating universe 
importance of, 218 
origins of discovery, 218-19 
Acetylcholine 

neurotransmitters, 145 
Achromatic microscope 
mitochondria, 103 
Adrenaline, 109 
Agassiz, Louis 
ice ages, 69-70 
Agglutination, 99 
Air pressure 

importance of, 17 
origins of discovery, 17-18 
Algae 

complete evolution, 209 
Amino acids. See also Tryptophan 
origins of life, 194-95 
vitamins, 118 
Anaerobic process 
metabolism, 174-75 

Anatomy. See Comparative anatomy; Human 
anatomy 
Anesthesia 

definition of, 57 
importance of, 57 
origins of discovery, 57-58 
Animals. See also Ecosystems; Plants 
coelacanth, 176-77 
continental drift, 138 
deep-sea life, 88-89 
order in nature, 33-34 
theory of evolution, 79-80 
Anthropology 

theory of evolution, 79 
Antibiotics 

importance of, 124 
origins of discovery, 124-25 
penicillin, 158-59 


Antimatter. See also Matter 
E = me 2 , 1 12 
importance of, 160 
origins of discovery, 160-61 
Apes 

human evolution, 146 
Archimedes 

levers and buoyancy, 3-4 
Aristotle 

Jupiter’s moons, 13 
law of falling objects, 9-10 
laws of motion, 3 1 
Arteries 

circulatory system, 15-16 
Astrology 

distance to the sun, 27 

Astronomy. See also Big Bang theory; Black 
holes; Expanding universe; Galaxies; 
Origins of life; Solar system; Speed 
of light; Sun-centered universe 
dark matter, 21 1-12 
distance to the sun, 27-28 
Doppler Effect, 75-76 
electromagnetic radiation/radio waves, 83 
existence of planets around other stars, 
215-16 

Infrared (IR) and ultraviolet (UV) light, 
55-56 

planetary motion, 11-12 
quasars and pulsars, 205-6 
Atmosphere. See also Ice ages; Nature of the 
atmosphere; Oceans, effects on 
weather; Oxygen; Weather 
air pressure, 17-18 
matter, 47-48 
origins of life, 194-95 
photosynthesis, 45 
Atmospheric layers 
importance of, 107 
origins of discovery, 107-8 
Atomic bonding 
importance of, 131 
origins of discovery, 131-32 


239 


240 Index 


Atomic energy 
fusion, 192-93 
isotopes, 133-34 
Atomic light signatures 
importance of, 81 
origins of discovery, 81-82 
Atomic weight 
isotopes, 133-34 

Periodic Chart of the Elements, 90-91 
Atoms. See also Big Bang theory; 

Electrochemical bonding; Electrons; 
Existence of cells; Hydrogen bomb; 
Isotopes; Molecules; Neutrons; Nuclear 
bomb; Nuclear fission; Radioactivity; 
Subatomic particles; Uncertainty 
Principle 
Boyle’s Law, 19 
importance of, 59 
origins of discovery, 59-60 
weak and strong force, 171-72 
ATP 

metabolism, 175 
Avogadro, Amedeo 

Avogadro’s Number, 63 
molecules, 63-64 

Bacteria. See also Antibiotics; Origins of life; 
Penicillin; Viruses 
complete evolution, 209 
germ theory, 77-78 
importance of, 29 
origins of discovery, 29-30 
Bakker, Robert 

nature of dinosaurs, 213-14 
Balloons 

atmospheric layers, 107 
Bandwidth 

definition of information, 189 
Banting, Frederick 
insulin, 1 42^43 
Bardeen, John 

semiconductor transistor, 183-84 
Barium 

nuclear fission, 178-79 
Barometer. See also Atmosphere; Weather 
air pressure, 17 
atmospheric layers, 107-8 
Batteries 

electrochemical bonding, 62 
electricity, 38 
“Voltaic Pile,” 62 


Bayliss, William 
hormones, 109-10 
Beadle, George 

genes, function of, 167-68 
Beijerinick, Martinus 
viruses, 101-2 

Bell, Jocelyn. See also Sandage, Allan Rex 
pulsars, 205-6 
Benda, Carl 

mitochondria, 103-4 
Beryllium 

neutrons, 164 

Big Bang theory. See also Accelerating 
universe 

expanding universe, 150 
importance of, 185 
origins of discovery, 185-86 
Binomial system, 34 
Biochemical genetics 

genes, function of, 167-68 
Biology. See also Complete evolution; 
Existence of cells; Microbiology; 
Molecular biology; Origins of life 
cell division, 92-93 
cell structure, 165-66 
chromosomes, function of, 121-22 
coelacanth, 176-77 
ecosystems, 169-70 
“jumping genes,” 191 
order in nature, 33-34 
theory of evolution, 79-80 
Birds 

nature of dinosaurs, 213 
“Bit of scruff,” 206 
Black holes 

importance of, 140 
origins of discovery, 140-41 
quasars and pulsars, 206 
“Black reaction,” 103 
Blood cells, 29 
Blood plasma 

importance of, 181 
origins of discovery, 181-82 
Blood sugar 

insulin, 142^13 
Blood transfusions 
plasma, 181-82 
Blood types 

importance of, 97 
origins of discovery, 97-98 


Index 241 


Bohr, Niels 

atomic bonding, 131-32 
Boltwood, Bertram 

radioactive dating, 119-20 
Bonding. See Atomic bonding; Electrochemical 
bonding 
Bone structure 

nature of dinosaurs, 214 
Boolean logic 

definition of information, 188 
Born, Max 

quantum theory, 148-49 
Botany 

order in nature, 33-34 
Boyle, Robert 

Boyle’s Law, 19-20 
Boyle’s Law 

importance of, 19 
origins of discovery, 19-20 
Brahe, Tycho 

planetary motion, 1 1-12 
Brain function 

neurotransmitters, 144—45 
Brown dwarfs 

existence of planets around other stars, 
215-16 

Bubble chamber, 203-4 
Buckland, William 

dinosaur fossils, 67-68 
Bunsen, Robert 

atomic light signatures, 81-82 
Bunsen burner, 82 
Buoyancy. See also Levers 
definition of, 3 
importance of, 4 
origins of discovery, 3-4 

Calculus, 31-32 
Caloric, 49-50 
Calories 

as units of energy, 7 1 
importance of, 7 1 
origins of discovery, 71-72 
vitamins, 117-18 
Cancer research 

cell structure, 165-66 
Capillaries, 29 
Carbon 

metabolism, 175 
radioactive dating, 120 


Carbon dioxide. See also Oxygen; 
Photosynthesis 

electrochemical bonding, 61-62 
metabolism, 175 
Cassini, Giovanni 
Cassini gaps, 27 
distance to the sun, 27-28 
Catastrophism 

erosion of Earth’s surface, 51 
Cathode rays 

electrons, 101-2 
Cell division 

importance of, 92 
origins of discovery, 92-93 
Cell structure 

importance of, 165 
origins of discovery, 165-66 
Cells. See Blood cells; Complete evolution; 
Existence of cells; Genes; 
Microbiology; Mitochondria; 
Neurotransmitters; Viruses 
Centrifuge 

cell structure, 166 
Chadwick, James 
neutrons, 163-64 
Chaos theory 

nature of the atmosphere, 201-2 
Chart of the Elements. See Periodic Chart of 
the Elements 
Chemical compounds 
antibiotics, 124—25 
isotopes, 133-34 
vitamins, 117-18 

Chemical messengers. See Hormones; 
Neurotransmitters 

Chemistry. See also Electrochemical 
bonding; Electrochemistry; 
Neurotransmitters; Periodic Chart of 
the Elements; Photochemistry 
atoms, 59-60 
Big Bang theory, 186 
Boyle’s Law, 19 
isotopes, 133-34 
matter, 47 
Chemotherapy 

antibiotics, 124—25 
Chloroform, 57 
Chromatic aberration, 103 
Chromatin, 93 


242 Index 


Chromosomes 

cell division, 92-93 
cell structure, 166 
function of, 121-23 
heredity, 86 
human genome, 22 1 
“jumping genes,” 190-91 
Circulatory system 
importance of, 15 
origins of discovery, 15-16 
Citric acid 

metabolism, 175 
Claude, Albert 

cell structure, 165-66 
Climate. See Atmospheric layers; Oceans, 
effects on weather 

Clouds 

atmospheric layers, 107 
Coelacanth 

importance of, 176 
origins of discovery, 176-77 
Combustion, 43-44, 49 
Communication 

neurotransmitters, 144—45 
Comparative anatomy 
nature of dinosaurs, 213 
Complete evolution 
importance of, 208 
origins of discovery, 208-9 
Compounds. See Chemical compounds; 

Inorganic compounds 
Computers 

definition of information, 188-89 
human genome, 221 

Conductivity. See Semiconductor transistor; 

Superconductivity 
Conservation of energy 
contradictions, 112 
importance of, 73 
origins of discovery, 73-74 
Conservation of mass 
contradictions, 112 

Continental drift. See also Earth’s core and 
mantle; Plate tectonics; Seafloor 
spreading 
importance of, 138 
origins of discovery, 138-39 
Copernicus, Nicholaus 
Jupiter’s moons, 13-14 
planetary motion, 1 1 
sun-centered universe, 5-6 


Core and mantle. See Earth’s core and 
mantle 
Corn research 

“jumping genes,” 190-91 

Corpuscular theory of matter 
fossils, 26 
Cortisone, 110 
“Cosmic egg,” 185 
“Cosmological constant,” 218 
Council of Cardinals 
Jupiter’s moons, 14 
Courtroom evidence 
DNA, 196 
Crick, Francis 
DNA, 196-97 
Crookes’ tube 
X-rays, 95-96 
Curie, Marie 

radioactivity, 105-6 
“Curvature of space, the” 
black holes, 140 
Cytoplasm 

mitochondria, 103 — 4 

Dalton, John 
atoms, 59-60 
“Dark energy,” 219 
Dark matter 

importance of, 211 
origins of discovery, 211-12 
Dart, Raymond 

human evolution, 146-47 
Darwin, Charles. See also Complete evolution 
dinosaur fossils, 67 
heredity, 86 

human evolution, 146-47 
theory of evolution, 79-80, 121 
Dating. See Radioactive dating 
Davy, Humphry 
anesthesia, 57-58 
electrochemical bonding, 61-62 
Decay. See Radioactive decay 
Decomposers 
ecosystems, 170 
Deep-sea life 

importance of, 88 
origins of discovery, 88-89 
Definition of information 
importance of, 188 
origins of discovery, 188-89 


Index 243 


Democritus 

Boyle’s Law, 19 
Density 

atmospheric layers, 107-8 
Big Bang theory, 185-86 
black holes, 140-41 
buoyancy, 4 

Earth’s core and mantle, 136-37 
nature of the atmosphere, 202 
quasars and pulsars, 205-6 
Deoxyribonucleic Acid (DNA). See also 

Human genome; mDNA; Origins of life; 
Ribonucleic Acid (RNA) 
chromosomes, function of, 121 
complete evolution, 208 
genes, function of, 167-68 
heredity, 86-87 
importance of, 196 
mitochondria, 103-4 
origins of discovery, 196-97 
Depths of the Sea, The, 89 
Detritus, 89 
Diabetes 

insulin, 142^13 

Dietary health. See also Nutrition 
vitamins, 117-18 
Diffraction patterns 

Earth’s core and mantle, 137 
Digestive juices 
insulin, 1 42^43 

Digital technology. See also Computers 
definition of information, 188 
Dinosaur fossils. See also Nature of dinosaurs 
importance of, 67 
origins of discovery, 67-68 
Dirac, Paul 

antimatter, 160-62 
Diseases. See Antibiotics; Bacteria; 

Deoxyribonucleic Acid (DNA); Human 
genome; “Jumping genes”; Penicillin; 
Vaccinations; Viruses; Vitamins 
Dissections 

circulatory system, 15 
human anatomy, 7-8 
Distance to the sun 
importance of, 27 
origins of discovery, 27-28 
DNA. See Deoxyribonucleic Acid (DNA) 
Doppler, Christian 

Doppler Effect, 75-76 


Doppler Effect 
Doppler shift, 76 
importance of, 75 
origins of discovery, 75-76 
Doppler shift, 76 

accelerating universe, 219 
dark matter, 212 

existence of planets around other stars, 215-16 
quasars and pulsars, 205 
Double helix model 
DNA, 197 

human genome, 220-21 
Drew, Charles 

blood plasma, 181-82 

E = me 2 

black holes, 140 
fusion, 192 
importance of. 111 
origins of discovery, 1 1 1-12 
speed of light, 155 
Earth’s core and mantle. See also 

Continental drift; Plate tectonics; 
Seafloor spreading 
importance of, 136 
origins of discovery, 136-37 
Earthquakes. See Fault lines 
Ecology 

nature of dinosaurs, 213 
theory of evolution, 79-80 
Ecosystems 

importance of, 169 
nature of dinosaurs, 213 
order in nature, 33 
origins of discovery, 169-70 
“Eddington’s equations,” 160 
Ehrlich, Paul 

antibiotics, 124—25 
Eijkman, Christiaan 
vitamins, 117-18 
Einstein, Albert 
E = me 2 , 111-13 
theory of relativity, 1 14-16 
Electrical currents 
antimatter, 160-61 
neurotransmitters, 144-45 
neutrons, 163 

semiconductor transistor, 183-84 
Electrical energy 

semiconductor transistor, 183-84 
superconductivity, 128-29 


244 Index 


Electrical fields 

electromagnetic radiation/radio waves, 84 
Electrical resistance 

semiconductor transistor, 183-84 
superconductivity, 128-29 
Electricity. See also Superconductivity 
conservation of energy, 74 
electromagnetic radiation/radio waves, 

83-84 

electromagnetism, 65-66 
electrons, 101 
importance of, 38 
origins of discovery, 38-39 
Electrochemical bonding 
importance of, 61 
origins of discovery, 61-62 
Electrochemistry 

infrared (IR) and ultraviolet (UV) light, 56 
metabolism, 175 
Electrodes, 62 
Electrolytes, 62 

Electromagnetic radiation/radio waves 
importance of, 83 
origins of discovery, 83-84 
quasars and pulsars, 206 
Electromagnetism 
electrons, 102 
importance of, 65 
origins of discovery, 65-66 
weak and strong force, 171-72 
Electron microscope 
atoms, 59 

cell structure, 165-66 
viruses, 97-98 
Electronic circuits 

definition of information, 188 
Electrons. See also Atomic bonding; 

Proton-electrons; Protons; 

Superconductivity; Uncertainty Principle 
antimatter, 160-61 
atoms, 59-60 
Big Bang theory, 186 
electrochemical bonding, 61-62 
importance of, 101 
isotopes, 134 
neutrons, 163 

origins of discovery, 101-2 
quantum theory, 148-49 
Elementary particles 
antimatter, 161 
Uncertainty Principle, 153 


Elements. See Periodic Chart of the 

Elements; Isotopes; Radioactive 
dating; Trace elements 
Ellipses. See also Epi-circles 
definition of, 12 
laws of motion, 3 1 
planetary motion, 11-12 
Endocrinology 

hormones, 109-10 
Energy. See Antimatter; Calories; 

Conservation of energy; “Dark 
energy;” Fission; Fusion; Kinetic 
energy; Metabolism; Nuclear fission; 
Solar energy 
Energy and matter 
antimatter, 161 
E = me 2 , 111-12 
theory of relativity, 115 
Enzymes 

genes, function of, 167-68 
metabolism, 175 
Epi-circles. See also Ellipses 
planetary motion, 11-12 
sun-centered universe, 5-6 
Epinephrine, 109 
Erosion of Earth’s surface 
importance of, 5 1 
origins of discovery, 51-52 
Escape velocity 
black holes, 141 
Ether, 58 
Event horizon 
black holes, 141 

Evolution. See Complete evolution; Human 
evolution; Theory of evolution 
Existence of cells 

cell, definition of, 22 
importance of, 21 
origins of discovery, 21-22 
Existence of planets around other stars 
importance of, 215 
origins of discovery, 215-16 
Expanding universe 

Big Bang theory, 185-86 
importance of, 150 
origins of discovery, 150-51 
Experiments Upon Vegetables, 46 

Falling objects. See Law of falling objects; 
Laws of motion 


Index 245 


Fault lines. See also San Andreas fault 
importance of, 126 
origins of discovery, 126-27 
Field data 
ice ages, 69 

Fission. See also Fusion; Nuclear fission 
radioactive dating, 119 
Fixed-order lines 

chromosomes, function of, 122 
Fleming, Alexander 
penicillin, 158-59 
Flemming, Walther 
cell division, 92-94 
“Fly Room, The,” 121 
Food 

metabolism, 174-75 
vitamins, 117-18 

Force. See also Weak and strong force 
laws of motion, 31-32 

Fossils. See also Coelacanth; Continental drift; 
Dinosaur fossils; Geology; Human 
evolution; Nature of dinosaurs; Origins 
of life 

definition of, 25 
importance of, 25 
“living fossil,” 176-77 
origins of discovery, 25-26 
seafloor spreading, 200 
Fractionation 

cell structure, 165-66 
Franklin, Benjamin 
electricity, 38-39 
oceans, effects on weather, 40-42 
Friction 

nature of heat, 49-50 
Fundamentals of Ecology, 170 
Fusion. See also Fission 
importance of, 192 
origins of discovery, 192-93 

Galaxies 

accelerating universe, 218-19 

atomic light signatures, 81-82 

dark matter, 212 

Doppler Effect, 75-76 

expanding universe, 150-51 

existence of planets around other stars, 216 

importance of, 36 

origins of discovery, 36-37 

quasars and pulsars, 206 

weak and strong force, 171-72 


Galen 

circulatory system, 15 
human anatomy, 7-8 
Galilei, Galileo 
air pressure, 17 
Jupiter’s moons, 13-14 
law of falling objects, 9-10 
laws of motion, 3 1 
sun-centered universe, 6 
Gamma rays. See also X-rays 

electromagnetic radiation/radio waves, 83 
infrared (IR) and ultraviolet (UV) light, 

55 

isotopes, 134 
Gamow, George 

Big Bang theory, 185-86 
Gas. See also Nitrous oxide; Oxygen 
anesthesia, 58 

atomic light signatures, 81-82 
Boyle’s Law, 19-20 
electrochemical bonding, 61 
matter, 47 
molecules, 63-64 
nature of the atmosphere, 202 
origins of life, 195 
Geiger counter, 120 
Gell-Mann, Murry 
quarks, 203-4 
Generators 
electricity, 38 

Genes. See also “Jumping genes” 
chromosomes, function of, 121 
function of, 167-68 
importance of, 167 
origins of discovery, 167-68 
Genetics. See Biochemical genetics; 

Chromosomes; Complete evolution; 

Heredity 

Genome. See Human genome 
Geology, 26, 52. See also Continental drift; 

Fault lines; Fossils; Ice ages; 

Isotopes; Radioactive dating 
Geophysics 

Earth’s core and mantle, 136-37 
Germ theory. See also Viruses 
importance of, 77 
origins of discovery, 77-78 
Germanium, 183-84 
Glaciers 

ice ages, 69-70 


246 Index 


Gravitation. See Accelerating universe; Air 

pressure; Conservation of energy; Law 
of falling objects; Laws of motion; 
Quasars and pulsars; Theory of 
relativity; Universal gravitation; Weak 
and strong force 
Gravitational pull 

accelerating universe, 218-19 
black holes, 140-41 

existence of planets around other stars, 215 
Gravitons 

weak and strong force, 172 
Gulf Stream, 40-41 
Gutenberg, Beno 

Earth’s core and mantle, 136-37 
Guyots, 199-200 

Half-life 

radioactive dating, 119 
Harvey, William 

circulatory system, 15-16 
Health. See Dietary health 
Heart 

circulatory system, 15 
Heat. See also Nature of heat; 
Thermodynamics 
atomic light signatures, 81-82 
calories, 71-72 
conservation of energy, 74 
fusion, 192-93 
metabolism, 174 

semiconductor transistor, 183-84 
Heisenberg, Werner 

Uncertainty Principle, 153-54 
Helium. See Liquid helium 
Heredity. See also Genes; Human genome 
cell division, 92-93 
importance of, 86 
origins of discovery, 86-87 
Herschel, Frederick 

Infrared (IR) light, 55-56 
Herschel, William 
galaxies, 36-37 
Hess, Harry 

seafloor spreading, 199-200 
Hewish, Antony. See also Bell, Jocelyn 
pulsars, 205-6 
Hooke, Robert 

existence of cells, 21-22 


Hopkins, Frederick 
vitamins, 117-18 
Homo sapiens, 33 
Hormones. See also Insulin 
importance of, 109 
origins of discovery, 109-10 
Hubble, Edwin 

expanding universe, 150-52 
Human anatomy. See also Circulatory 

system; Existence of cells; Fossils 
genes, function of, 168 
importance of, 7 
metabolism, 174-75 
origins of discovery, 7-8 
vitamins, 117-18 
Human evolution 
importance of, 146 
origins of discovery, 1 46-47 
Human genome 
DNA, 196 
importance of, 220 
origins of discovery, 220-21 
Human species 
DNA, 196-97 
order in nature, 33 
Humanoids 

human evolution, 147 
Humidity 

atmospheric layers, 107-8 
Hutton, James 

erosion of Earth’s surface, 51-52 
Hydrogen bomb 
fusion, 192-93 

Ice ages 

importance of, 69 
origins of discovery, 69-70 
Iguanodon, 68 
Immune system 
antibiotics, 124-25 
Infections. See Antibiotics; Bacteria; 

Diseases; Penicillin; Vaccinations; 
Viruses 
Influenza 

penicillin, 159 

Information. See Definition of information 
Information Age 

definition of information, 188 
Information streams 

definition of information, 189 


Index 247 


Infrared (IR) and ultraviolet (UV) light 
importance of, 55 
origins of discovery, 55-56 
Ingenhousz, Jan 

photosynthesis, 45-46 
Ingrafting, 53 
Inorganic compounds 
origins of life, 194-95 
Insulin 

importance of, 142 
origins of discovery, 1 42-43 
Isotopes 

importance of, 133 
origins of discovery, 133-34 
radioactive dating, 119-20 
Ivanovsky, Dmitri 
viruses, 101-102 

Jenner, Edward. See also Montagu, Lady Mary 
Wortley 

vaccinations, 53-54 
Joule, James 
calories, 71-72 
“Jumping genes” 
importance of, 190 
origins of discovery, 190-91 
Jupiter’s moons 
importance of, 13 
origins of discovery, 13-14 

Kelvin, Lord 
fusion, 192 

superconductivity, 128 
Kepler, Johannes 

distance to the sun, 27 
laws of motion, 3 1 
planetary motion, 1 1-12 
sun-centered universe, 6 
Kinetic energy 

conservation of energy, 73-74 
Kirchhoff, Gustav 

atomic light signatures, 81-82 
Krebs, Hans Adolf 
metabolism, 174-75 

Lactic acid 

metabolism, 174-75 
Landsteiner, Karl 
blood types, 97-98 


Latitudinal zonation 

nature of dinosaurs, 213 
Lavoisier, Antoine 
matter, 47-48 

Law of falling objects. See also Planetary 
motion; Universal gravitation 
importance of, 9 
origins of discovery, 9-10 
Laws of motion. See also Dark matter; 
Planetary motion; Universal 
gravitation 
importance of, 3 1 
origins of discovery, 31-32 
Lead. See also Uranium 
radioactive dating, 120 
Leeuwenhoek, Anton van 
bacteria, 29-30 
Levers. See also Buoyancy 
definition of, 3 
importance of, 3 
origins of discovery, 3-4 
Life. See Origins of life 
Light. See also Dark matter; E = me 2 ; 

Infrared (IR) and ultraviolet (UV) 
light; Speed of light 
accelerating universe, 218-19 
atomic light signatures, 8 1 
black holes, 140-41 
conservation of energy, 74 
deep-sea life, 88-89 
electricity, 38 

existence of planets around other stars, 
215-16 

quasars and pulsars, 205-6 
semiconductor transistor, 183-84 
Light, space, and time 
black holes, 140-41 
E = me 2 , 111-12 
theory of relativity, 1 14-15 
Light waves 

Doppler Effect, 75-76 
Light years 

quasars and pulsars, 206 
speed of light, 155-56 
Lightning 

electricity, 38-39 
lightning rod, 39 
Linnaeus, Carl 

order in nature, 33-35 
Liquid helium 

superconductivity, 129 


248 Index 


Liquid mercury 
air pressure, 17 
Boyle’s Law, 20 
superconductivity, 129 
Loewi, Otto 

neurotransmitters, 144—45 
Logarithms 

planetary motion, 12 
Lorenz, Ed 

nature of the atmosphere, 201-2 
Lungs 

circulatory system, 15 

“Magic bullet,” 125 
Magma 

seafloor spreading, 200 
Magnetic fields 
fusion, 193 

Magnetism. See also Electromagnetic 

radiation/radio waves; Electromagnetism 
conservation of energy, 74 
electrons, 101-2 
Mantell, Gideon 

dinosaur fossils, 67-68 
Mantle. See Earth’s core and mantle 
Margulis, Lynn 

complete evolution, 208-9 
Marine science 
coelacanth, 177 

Mathematics. See also Nonlinear model 
equations 

accelerating universe, 218-19 
antimatter, 160-61 
Big Bang theory, 186 
definition of information, 188-89 
E = me 2 , 111-12 
fusion, 192-93 

nature of the atmosphere, 201-2 
quantum theory, 148 
superconductivity, 129 
theory of relativity, 114 
Uncertainty Principle, 153-54 
Matrix mechanics 

Uncertainty Principle, 153-54 
Matter. See also Antimatter; Dark matter; E = 
me 2 ; Energy and matter 
atoms, 59-60 
Big Bang theory, 185-86 
conservation of, 47-48 
definition of information, 188-89 
fusion, 192-93 


importance of, 47 
laws of motion, 31-32 
origins of discovery, 47-48 
oxygen, 43 
photosynthesis, 46 
quarks, 203-4 
Maxwell, James Clerk 

electromagnetic radiation/radio waves, 83-85 
Mayor, Michel 

existence of planets around other stars, 
215-16 

McClintock, Barbara 

“jumping genes,” 190-91 
mDNA 

mitochondria, 104 
Measurement 

accelerating universe, 219 
antimatter, 161 
Big Bang theory, 185-86 
Doppler Effect, 76 
E = me 2 , 112 

existence of planets around other stars, 
215-16 
fusion, 192-93 
matter, 47-48 
speed of light, 155-56 
Medicine 

anesthesia, 57-58 
human anatomy, 7-8 
Megalosaurus, 68 
Meitner, Lise 

nuclear fission, 178-80 
Mendel, Gregor 
heredity, 86-87 
Mendeleyev, Dmitri 

Periodic Chart of the Elements, 90-91 
Mercury. See Liquid mercury 
Mesons. See also Pi-mesons 
weak and strong force, 172 
Metabolism 

importance of, 174 
origins of discovery, 174-75 
Meteorology. See Atmosphere; Atmospheric 
layers; Barometer; Oceans, effects on 
weather; Weather 
Michelson, Albert 

speed of light, 155-56 
Microbiology 
bacteria, 29-30 
mitochondria, 103-4 
germ theory, 78 


Index 249 


Microorganisms 
antibiotics, 124-25 
germ theory, 77-78 

Microscopes. See also Achromatic microscope; 
Antibiotics; Electron microscope; 
Telescopes 
bacteria, 29-30 
cell division, 92-93 
existence of cells, 21 
dark matter, 211 
fossils, 26 

“jumping genes,” 191 
mitochondria, 103 
quantum theory, 148-49 
viruses, 97-98 
Microscopic organisms 
antibiotics, 124 
germ theory, 77-78 
Microwaves 

infrared (IR) and ultraviolet (UV) light, 55 
Milky Way, 36 
Miller, Stanley 

origins of life, 194-95 
“Mind (or thought) experiments” 

Einstein, Albert, 111, 115 
“Missing link,” 147 

Mitochondria. See also Cell structure; Complete 
evolution 
importance of, 103 
origins of discovery, 103-4 
Mitosis. See Cell division 
Mold 

genes, function of, 168 
penicillin, 159 
Molecular biology 
DNA, 196-97 

Molecules. See also Atoms; Protein molecules 
definition of, 64 
DNA, 196-97 
importance of, 63 
origins of discovery, 63-64 
X-rays, 95 
Momentum 

conservation of energy, 74 
Montagu, Lady Mary Wortley. See also Jenner, 
Edward 

vaccinations, 53-54 
Moons. See Jupiter’s moons 
Morgan, T. H. 

chromosomes, function of, 121-23 


Motion. See also Black holes; Dark matter; 
Law of falling objects; Laws of 
motion; Momentum; Uncertainty 
Principle 

accelerating universe, 218-19 
nature of heat, 50 
nature of the atmosphere, 202 
quasars and pulsars, 205-6 
seafloor spreading, 199-200 
Motors 

electricity, 38 
electromagnetism, 65 
Muscles 

metabolism, 174-75 
Mutations 

chromosomes, function of, 121-22 
complete evolution, 208-9 
genes, function of, 168 
“jumping genes,” 191 

Napier, John 

planetary motion, 12 
Natural selection 

complete evolution, 208-9 
theory of evolution, 80 
Naturalist’s Voyage on the Beagle, A 
theory of evolution, 80 
Nature. See Order in nature 
Nature of dinosaurs 
importance of, 213 
origins of discovery, 213-14 
Nature of heat 

importance of, 49 
origins of discovery, 49-50 
Nature of the atmosphere 
importance of, 201 
origins of discovery, 201-2 
Neosalvarsan 
antibiotics, 125 
Neurons, 144-45 
Neurospora 

genes, function of, 167 
Neurotransmitters 
importance of, 144 
origins of discovery, 144-45 
Neutrinos 

antimatter, 161 
Neutron star, 206 


250 Index 


Neutrons. See also Electrons; Protons; Quarks 
antimatter, 161 
Big Bang theory, 186 
importance of, 163 
isotopes, 134 

origins of discovery, 163-64 
weak and strong force, 172 
Newton, Isaac 
air pressure, 17 
law of falling objects, 9 
laws of motion, 31-32 
universal gravitation, 23-24 
Nitrogen cycle 
ecosystems, 169 
Nitrous oxide 
anesthesia, 58 

electrochemical bonding, 61 
Nonlinear model equations 
nature of the atmosphere, 202 
Nuclear bomb 

Big Bang theory, 186 
E = me 2 , 111-12 
fission, 179 
neutrons, 163 
Nuclear energy 
E = me 2 , 111-12 
fission, 178-79 
fusion, 192-93 
quantum theory, 148-49 
speed of light, 156 
Nuclear fission 

importance of, 178 
origins of discovery, 178-79 
Nucleus. See also Atomic bonding; Cell 
structure; Cells 
isotopes, 133-34 
mitochondria, 103 
neutrons, 163-64 
Uncertainty Principle, 153 
Nutrition 

vitamins, 117-18 

Oceans, effects on weather. See also Deep-sea 
life 

importance of, 40 
origins of discovery, 40-41 
Oersted, Hans 

electromagnetism, 65-66 
Onnes, Heike Kamerlingh 
superconductivity, 128-30 


Order in nature 
importance of, 33 
origins of discovery, 33-34 
Organelles 

cell structure, 166 
mitochondria, 103 
Origin of Species 

theory of evolution, 80 
Origins of life 

importance of, 194 
origins of discovery, 194-95 
Original Theory on New Hypothesis of the 
Universe, An, 37 
Oxidation 

nature of heat, 49 

Oxygen. See also Gas; Photosynthesis 
atmospheric layers, 107 
importance of, 43 
metabolism, 174-75 
origins of discovery, 43-44 

Paleontology. See also Anthropology; 
Nature of dinosaurs 
dinosaur fossils, 67 
theory of evolution, 79 
Pancreas 
insulin, 142 
Pangaea, 139 

Particle physics. See also Elementary 
particles; Subatomic particles 
electrons, 101-2 
Pasteur, Louis 
bacteria, 30 
germ theory, 77-78 
Pasteurization, 77-78 
Penicillin 

antibiotics, 124 
importance of, 158 
origins of discovery, 158-59 
Periodic Chart of the Elements 
importance of, 90 
isotopes, 133 

origins of discovery, 90-91 
Perlmutter, Saul 

accelerating universe, 218-19 
Pharmacology 

antibiotics, 124—25 
neurotransmitters, 145 
Phlogiston, 49 
Phosphates 

metabolism, 175 


Index 251 


Photochemistry 

atomic light signatures, 82 
Photons 

E = me 2 , 1 1 1 

Photosynthesis. See also Oxygen; Plants 
importance of, 45 
origins of discovery, 45—46 
Physics. See also Atomic bonding; E = me 2 ; 

Energy and matter; Geophysics; Particle 
physics; Quantum physics; Quantum 
theory; Speed of light; Theory of 
relativity; Uncertainty Principle 
antimatter, 160-61 
atoms, 59-60 
Big Bang theory, 185-86 
dark matter, 211-12 
electromagnetic radiation/radio waves, 
83-84 

isotopes, 133-34 
nuclear fission, 178-79 
radioactivity, 105-6 
superconductivity, 128-29 
weak and strong force, 171-72 
Physiology. See Antibiotics; Circulatory 

system; Hormones; Human anatomy; 
Vitamins 
Pi-mesons 

weak and strong force, 172 
Pistons 

Boyle’s Law, 19-20 
Pitchblende, 105 
Plague 

vaccinations, 53-54 

Planetary motion. See also Galaxies; Law of 
falling objects; Laws of motion 
importance of, 1 1 
origins of discovery, 11-12 
tables of calculations, 12 
Planets. See Existence of planets around other 
stars 

Plants. See also Algae; Animals; Ecosystems; 
Photosynthesis 
bacteria, 29 

complete evolution, 209 
continental drift, 138 
deep-sea life, 88-89 
order in nature, 33-34 
radioactive dating, 119-20 
theory of evolution, 79-80 
Plasma. See Blood plasma 


Plate tectonics. See also Continental drift; 

Seafloor spreading 
fault lines, 126-27 
Polonium, 105-6 
Positrons 

antimatter, 161 
Potassium 

electrochemical bonding, 61-62 
Priestley, Joseph 
oxygen, 43-44 
Principia, 32 
Prism 

atomic light signatures, 82 
Protein molecules 
vitamins, 118 
Proton-electrons 
neutrons, 163-64 

Protons. See also Electrons; Quarks 
antimatter, 160-61 
Big Bang theory, 186 
isotopes, 133-34 
nuclear fission, 178-79 
quantum theory, 148-49 
Uncertainty Principle, 153 
weak and strong force, 171-72 
Protozoa, 29 
Ptolemy 

Jupiter’s moons, 13 
law of falling objects, 9 
Ptolemy’s model, 5-6 
Pulsars. See Quasars and pulsars 
Pure air. See also Oxygen 
matter, 47 

Quanta 

atomic bonding, 132 
E = me 2 , 1 1 1 

Quantum electrodynamics 
antimatter, 160 
Quantum mechanics 
antimatter, 160-61 
quantum theory, 148-49 
Quantum physics 
antimatter, 160 
strangeness, 204 
weak and strong force, 171 
Quantum theory 

Big Bang theory, 186 
importance of, 148 
origins of discovery, 148-49 
superconductivity, 129 


252 Index 


Quarks 

importance of, 203 
origins of discovery, 203-4 
weak and strong force, 172 
Quasars and pulsars 
importance of, 205 
origins of discovery, 205-6 
Queloz, Didier 

existence of planets around other stars, 
215-16 

Radiation. See Atomic bonding; Big Bang 
theory; Dark matter; Electromagnetic 
radiation/radio waves; Infrared (IR) and 
ultraviolet (UV) light; Solar radiation 
Radiation sickness, 105 
Radioactive dating. See also Isotopes 
importance of, 119 
origins of discovery, 119-20 
Radioactive decay 
nuclear fission, 178 
weak and strong force, 171 
Radioactivity 

importance of, 105 
origins of discovery, 105-6 
polonium, 105-6 
radium, 105-6 
splitting of the atom, 105-6 
Radio signals 

quasars and pulsars, 205-6 
Radio waves. See Electromagnetic 
radiation/radio waves 
Radium, 105-6 
Recyclers 

ecosystems, 170 
Reid, Harry 

fault lines, 126-27 
Relativity. See Theory of relativity 
Reproduction. See Sexual reproduction 
Ribonucleic Acid (RNA) 
cell structure, 166 
Ribosomes 

cell structure, 166 
Ricci, Ostilio 

law of falling objects, 10 
Richer, Jean 

distance to the sun, 28 
Ritter, Johann 

ultraviolet (UV) light, 56 
Roentgen, Wilhelm 
X-rays, 95-96 


Rubbia, Carlo 

weak force, 171-72 
Rubin, Vera 

dark matter, 211-12 
Rumford, Count 

nature of heat, 49-50 

San Andreas fault, 127 
Sandage, Allan Rex 
quasars, 205-6 
Schwarzschild, Karl 
black holes, 140-41 
Seafloor spreading 
importance of, 199 
origins of discovery, 199-200 
Secretin, 1 10 
Sedimentation 
fossils, 26 
Seismic waves 

Earth’s core and mantle, 137 
Seismology. See also Fault lines; Geology 
Earth’s core and mantle, 136-37 
Semiconductor transistor 
importance of, 183 
origins of discovery, 183-84 
Sexual reproduction 
order in nature, 34 
Shadow zone, 136 
Shannon, Claude 

definition of information, 188-89 
Shipping 

oceans, effects on weather, 41 
Smith, J. L. B. 

coelacanth, 176-77 
Soddy, Frederick 
isotopes, 133-35 
Sodium 

electrochemical bonding, 61-62 
Solar energy 
fusion, 192-93 
Solar radiation 

atomic light signatures, 81-82 
Solar system. See also Distance to the sun; 

Galaxies 

existence of planets around other stars, 
215-16 

planetary motion, 11-12 
Sonar 

seafloor spreading, 199-200 
Sound 

conservation of energy, 74 


Index 253 


Sound waves 

Doppler Effect, 75-76 
Space. See Light, space, and time 
Spectrographs 

dark matter, 211-12 
distance to the sun, 27 
existence of planets around other stars, 216 
expanding universe, 151 
quasars and pulsars, 205 
Spectrography 

atomic light signatures, 8 1 
isotopes, 134 
quasars and pulsars, 205 
radioactive dating, 120 
Speed of light 
black holes, 141 
distance to the sun, 27 
E = me 2 , 111-12 

electromagnetic radiation/radio waves, 84 
importance of, 155 
origins of discovery, 155-56 
quarks, 203-4 
Sperm, 29 
Spitzer, Lyman 
fusion, 192-93 
Starling, Ernst 

hormones, 109-10 

Stars. See Atomic light signatures; Black holes; 
Distance to the sun; Doppler Effect; 
Existence of planets around other stars; 
Expanding universe; Galaxies; Neutron 
star; Quasars and pulsars; Solar system; 
Stellarator; Supernovae 

Static 

electricity, 38-39 
Stellarator 
fusion, 193 
Steno, Nicholas 
fossils, 25-26 
Strangeness 
quarks, 204 
Stratosphere 

atmospheric layers, 108 
Strong force. See Weak and strong force 
Subatomic particles. See also Atomic bonding; 
Quantum theory; Quarks 
antimatter, 160-61 
electrons, 101-2 
isotopes, 133 
neutrons, 163 


radioactivity, 105-6 
weak and strong force, 172 
Sugar 

metabolism, 174-75 

Sun-centered universe. See also Distance to 
the sun; Galaxies 
importance of, 5 
origins of discovery, 5-6 
Ptolemy’s model, 5-6 
Sunlight 

photosynthesis, 46 
Superconductivity 
importance of, 128 
origins of discovery, 128-29 
semiconductor transistor, 184 
Supernovae 

accelerating universe, 218 
quasars and pulsars, 206 
Supplements. See Vitamins 
Symbiosis 

complete evolution, 208-9 
Synchrotron 

weak and strong force, 172 
Systema Naturae, 34 

Tansley, Arthur 

ecosystems, 169-70 
Taung skull 

human evolution, 146-47 
Taxonomy. See also Order in nature 
definition of, 33 

Teisserenc de Bort, Leon Philippe 
atmospheric layers, 107-8 
Telescopes. See also Microscopes 
atmospheric layers, 108 
dark matter, 21 1-12 
definition of, 14 
distance to the sun, 27-28 
Doppler Effect, 76 

existence of planets around other stars, 
215-16 

expanding universe, 150-51 
planetary motion, 13 
radio, 205 

Temperature. See also Absolute zero temperature 
atmospheric layers, 107-8 
Big Bang theory, 186 
Earth’s core and mantle, 136-37 
fusion, 192-93 

infrared (IR) and ultraviolet (UV) light, 55 


254 Index 


Temperature ( Cont .) 
nature of heat, 50 
nature of the atmosphere, 202 
oceans, effects on weather, 40-41 
superconductivity, 128-29 
Theory of evolution. See also Heredity 
chromosomes, function of, 121 
importance of, 79 
origins of discovery, 79-80 
Theory of relativity 
black holes, 140 
E = me 2 , 112 
importance of, 114 
origins of discovery, 114-15 
Thermodynamics 
calories, 71 

conservation of energy, 73 
Thermometer 

atmospheric layers, 107 
superconductivity, 129 
Thompson, Benjamin. See Rumford, Count 
Thomson, Charles 
deep-sea life, 88-89 
Thomson, J. J. 

electrons, 101-2 
Thorium 

isotopes, 134 
radioactive dating, 119 
Time. See Light, space, and time 
Torricelli, Evangelista 
air pressure, 17-18 
Trace elements 
vitamins, 117-18 
Traits. See also Genes 

chromosomes, function of, 121 
heredity, 86-87 
Transfer resistors 

semiconductor transistor, 184 
Transfusions 

blood types, 100 

Transistor. See Semiconductor transistor 
Transverse waves 

Earth’s core and mantle, 137 
Troposphere 

atmospheric layers, 108 
Tryptophan 
vitamins, 118 

Ultraviolet (UV) light. See Infrared (IR) and 
ultraviolet (UV) light 


Uncertainty Principle 
importance of, 153 
origins of discovery, 153-54 
Universal gravitation. See also Law of 
falling objects; Laws of motion 
importance of, 23 
origins of discovery, 23-24 
Universe. See Accelerating universe; Dark 
matter; Existence of planets around 
other stars; Expanding universe; 
Quasars and pulsars 
Uranium. See also Lead 
isotopes, 134 
radioactive dating, 119 
radioactivity, 105-6 
Urkraft 

electromagnetism, 65-66 
infrared (IR) and ultraviolet (UV) light, 
56 

Vaccinations 

importance of, 53 
origins of discovery, 53-54 
Vacuum 

air pressure, 17-18 
matter, 48 
Vagus nerve 

neurotransmitters, 145 
Vagusstoff. See Acetylcholine 
van Helmholtz, Hermann 

conservation of energy, 73-7 4 
“Variation,” 208 
Vegetation zones 
ecosystems, 169 
Veins 

circulatory system, 15-16 
Venter, J. Craig 

human genome, 220-21 
Vesalius, Andreas 
human anatomy, 7-8 

Viruses. See also Antibiotics; Bacteria; Cell 
structure 

importance of, 97 
origins of discovery, 97-98 
“Vital force” theory 
conservation of energy, 73 
Vitamins 

definition of, 118 
importance of, 117 
origins of discovery, 1 17-18 


Index 255 


Volume 

Boyle’s Law, 20 
buoyancy, 4 
gas, 19-20 

oceans, effects on weather, 41 
Water 

air pressure, 17 
Watson, James 
DNA, 196-7 
human genome, 220-2 1 
Weak and strong force 
definitions of, 171-72 
importance of, 171 
origins of discovery, 171-72 
Weapons advancement 
E = me 2 , 112 
isotopes, 133 
nuclear fission, 178-79 
speed of light, 156 

Weather. See also Atmosphere; Barometer; 

Oceans, effects on weather; Troposphere 
air pressure, 17-18 
atmospheric layers, 107-8 
forecasting, 201-2 
ice ages, 69-70 
nature of the atmosphere, 202 
Wegener, Alfred 

continental drift, 138-39 


Weight. See also Atomic weight; Matter 
air pressure, 17-18 
atoms, 60 
Boyle’s Law, 20 
law of falling objects, 9-10 
levers, 3 
Wind 

atmospheric layers, 107 
Wobble effect 

existence of planets around other stars, 
215-16 
Wright, Thomas 
galaxies, 36-37 

X-ray crystalography 
penicillin, 159 

X-rays. See also Gamma rays 
dark matter, 212 
DNA, 196-97 

electromagnetic radiation/radio waves, 83-84 
genes, function of, 167-68 
importance of, 95 

infrared (IR) and ultraviolet (UV) light, 55 
origins of discovery, 95-96 

Yukawa, Hideki 

strong force, 171-72 

Zonation. See Latitudinal zonation 



About the Author 


Kendall Haven. The only West Point graduate and 
only senior oceanographer to become a professional sto- 
ryteller, Haven has performed for four million. He has 
won numerous awards for his story writing and his story- 
telling and has conducted story writing and storytelling 
workshops for 40,000 teachers and librarians and 
200,000 students. Haven has published five audiotapes 
and twenty-five books, including three award-winning 
books on story: Write Right and Get It Write on writing, 
and Super Simple Storytelling, on doing, using, and 
teaching storytelling. Through this work he has become a 
nationally recognized expert on the architecture of narra- 
tives and on teaching creative and expository writing. 

Haven served on the National Storytelling Associa- 
tion’s Board of Directors and founded the International 
Whole Language Umbrella’s Storytelling Interest 
Group. He served as co-director of the Sonoma and Bay Area Storytelling Festivals, was an 
advisor to the Mariposa Storytelling Festival, and is founder of Storytelling Festivals in Las 
Vegas, Nevada, and Boise, Idaho. He lives with his wife in the rolling Sonoma County 
grape vineyards in rural Northern California.